"""Some miscellaneous utility functions."""
import os
import re
import sys
import types
import unittest
from contextlib import contextmanager
from fnmatch import fnmatchcase
from io import StringIO
from numbers import Integral
from inspect import currentframe, getouterframes
from collections.abc import Iterable
import numpy as np
from openmdao.core.constants import INF_BOUND
from openmdao.utils.om_warnings import issue_warning, warn_deprecation
from openmdao.utils.array_utils import shape_to_len
_float_inf = float('inf')
def _convert_auto_ivc_to_conn_name(conns_dict, name):
"""
Convert name of auto_ivc val to promoted input name.
Parameters
----------
conns_dict : dict
Dictionary of global connections.
name : str
Name of auto_ivc to be found.
Returns
-------
str
Promoted input name.
"""
for key, val in conns_dict.items():
if val == name:
return key
[docs]def simple_warning(msg, category=UserWarning, stacklevel=2):
"""
Display a simple warning message without the annoying extra line showing the warning call.
Parameters
----------
msg : str
The warning message.
category : class
The warning class.
stacklevel : int
Number of levels up the stack to identify as the warning location.
"""
warn_deprecation('simple_warning is deprecated. '
'Use openmdao.utils.om_warnings.issue_warning instead.')
issue_warning(msg, stacklevel=stacklevel, category=category)
[docs]def ensure_compatible(name, value, shape=None, indices=None):
"""
Make value compatible with the specified shape or the shape of indices.
Parameters
----------
name : str
The name of the value.
value : float or list or tuple or ndarray or Iterable
The value of a variable.
shape : int or tuple or list or None
The expected or desired shape of the value.
indices : Indexer or None
The indices into a source variable.
Returns
-------
ndarray
The value in a shape compatible with the specified shape and/or indices.
tuple
The resulting shape of the value.
Raises
------
ValueError
If value cannot be made to conform to shape or if shape and indices
are incompatible.
"""
if isinstance(value, Iterable):
value = np.asarray(value)
# if shape is not given, infer from value (if not scalar) or indices
if shape is not None:
if isinstance(shape, Integral):
shape = (shape,)
elif isinstance(shape, list):
shape = tuple(shape)
elif not np.isscalar(value):
shape = np.atleast_1d(value).shape
if indices is not None:
if not indices._flat_src and shape is None:
raise RuntimeError(f"src_indices for '{name}' is not flat, so its input "
"shape must be provided.")
try:
indshape = indices.indexed_src_shape
except (RuntimeError, ValueError, TypeError):
pass # use shape provided or shape of value and check vs. shape of indices later
else:
if shape is not None and shape_to_len(indshape) != shape_to_len(shape):
raise ValueError(f"Shape of indices {indshape} does not match shape of {shape} for"
f" '{name}'.")
if shape is None:
shape = indshape
if shape is None:
# shape is not determined, assume the shape of value was intended
value = np.atleast_1d(value)
shape = value.shape
else:
# shape is determined, if value is scalar assign it to array of shape
# otherwise make sure value is an array of the determined shape
if np.ndim(value) == 0 or value.shape == (1,):
value = np.full(shape, value)
else:
value = np.atleast_1d(value).astype(np.float64)
if value.shape != shape:
raise ValueError(f"Incompatible shape for '{name}': Expected {shape} but got "
f"{value.shape}.")
return value, shape
[docs]def determine_adder_scaler(ref0, ref, adder, scaler):
r"""
Determine proper values of adder and scaler based on user arguments.
Adder and Scaler are used internally because the transformation is
slightly more efficient.
Parameters
----------
ref0 : float or ndarray, optional
Value of response variable that scales to 0.0 in the driver.
ref : float or ndarray, optional
Value of response variable that scales to 1.0 in the driver.
adder : float or ndarray, optional
Value to add to the model value to get the scaled value. Adder
is first in precedence.
scaler : float or ndarray, optional
Value to multiply the model value to get the scaled value. Scaler
is second in precedence.
Returns
-------
tuple
Adder and scaler, properly formatted and based on ref/ref0 if provided.
Raises
------
ValueError
If both ref/ref0 and adder/scaler were provided.
Notes
-----
The response can be scaled using ref and ref0.
The argument :code:`ref0` represents the physical value when the scaled value is 0.
The argument :code:`ref` represents the physical value when the scaled value is 1.
"""
# Affine scaling cannot be used with scalers/adders
if ref0 is not None or ref is not None:
if scaler is not None or adder is not None:
raise ValueError('Inputs ref/ref0 are mutually exclusive '
'with scaler/adder')
if ref is None:
ref = 1.0
if ref0 is None:
ref0 = 0.0
# Convert ref/ref0 to scaler/adder so we can scale the bounds
adder = -ref0
scaler = 1.0 / (ref + adder)
else:
if scaler is None:
scaler = 1.0
if adder is None:
adder = 0.0
adder = format_as_float_or_array('adder', adder, val_if_none=0.0, flatten=True)
scaler = format_as_float_or_array('scaler', scaler, val_if_none=1.0, flatten=True)
return adder, scaler
[docs]def set_pyoptsparse_opt(optname, fallback=True):
"""
For testing, sets the pyoptsparse optimizer using the given optimizer name.
This may be modified based on the value of OPENMDAO_FORCE_PYOPTSPARSE_OPT.
This can be used on systems that have SNOPT installed to force them to use
SLSQP in order to mimic our test machines on travis and appveyor.
Parameters
----------
optname : str
Name of pyoptsparse optimizer that is requested by the test.
fallback : bool
If True, fall back to SLSQP if optname can't be found.
Returns
-------
object
Pyoptsparse optimizer instance.
str
Pyoptsparse optimizer string.
"""
OPT = None
opt = None
OPTIMIZER = None
force = os.environ.get('OPENMDAO_FORCE_PYOPTSPARSE_OPT')
if force:
optname = force
from unittest.mock import Mock
try:
from pyoptsparse import OPT
try:
opt = OPT(optname)
OPTIMIZER = optname
except Exception:
if fallback and optname != 'SLSQP':
try:
opt = OPT('SLSQP')
OPTIMIZER = 'SLSQP'
except Exception:
pass
else:
if fallback and isinstance(opt, Mock):
try:
opt = OPT('SLSQP')
OPTIMIZER = 'SLSQP'
except Exception:
pass
except Exception:
pass
if isinstance(opt, Mock):
OPT = OPTIMIZER = None
if not fallback and OPTIMIZER != optname:
raise unittest.SkipTest("pyoptsparse is not providing %s" % optname)
return OPT, OPTIMIZER
[docs]class ContainsAll(object):
"""
A fake dictionary that always reports __contains__(name) to be True.
"""
[docs] def __contains__(self, name):
"""
Return if the named object is contained.
Parameters
----------
name : str
Name of the object being looked up.
Returns
-------
bool
Always returns True.
"""
return True
[docs]def all_ancestors(pathname, delim='.'):
"""
Return a generator of pathnames of the starting object and all of its parents.
Pathnames are ordered from longest to shortest.
Parameters
----------
pathname : str
Pathname of starting object.
delim : str
Delimiter used to split the name.
Yields
------
str
"""
parts = pathname.split(delim)
for i in range(len(parts), 0, -1):
yield delim.join(parts[:i])
[docs]def find_matches(pattern, var_list):
"""
Return list of variable names that match given pattern.
Parameters
----------
pattern : str
Glob pattern or variable name.
var_list : list of str
List of variable names to search for pattern.
Returns
-------
list
Variable names that match pattern.
"""
if pattern == '*':
return var_list
elif pattern in var_list:
return [pattern]
return [name for name in var_list if fnmatchcase(name, pattern)]
def _find_dict_meta(dct, key):
"""
Return True if the given key is found in any metadata values in the given dict.
Parameters
----------
dct : dict
The metadata dictionary (a dict of dicts).
key : str
The metadata key being searched for.
Returns
-------
bool
True if non-None metadata at the given key was found.
"""
for meta in dct.values():
if key in meta and meta[key] is not None:
return True
return False
[docs]def pad_name(name, pad_num=10, quotes=False):
"""
Pad a string so that they all line up when stacked.
Parameters
----------
name : str
The string to pad.
pad_num : int
The number of total spaces the string should take up.
quotes : bool
If name should be quoted.
Returns
-------
str
Padded string.
"""
name = f"'{name}'" if quotes else name
if pad_num > len(name):
return f"{name:<{pad_num}}"
else:
return f'{name}'
[docs]def add_border(msg, borderstr='=', vpad=0):
"""
Add border lines before and after a message.
The message is assumed not to span multiple lines.
Parameters
----------
msg : str
The message to be enclosed in a border.
borderstr : str
The repeating string to be used in the border.
vpad : int
The number of blank lines between the border and the message (before and after).
Returns
-------
str
A string containing the original message enclosed in a border.
"""
border = len(msg) * borderstr
# handle borderstr of more than 1 char
border = border[:len(msg)]
return f"{border}\n{msg}\n{border}"
[docs]def run_model(prob, ignore_exception=False):
"""
Call `run_model` on problem and capture output.
Parameters
----------
prob : Problem
An instance of Problem.
ignore_exception : bool
Set to True to ignore an exception of any kind.
Returns
-------
string
Output from calling `run_model` on the Problem, captured from stdout.
"""
stdout = sys.stdout
strout = StringIO()
sys.stdout = strout
try:
prob.run_model()
except Exception as err:
if not ignore_exception:
raise err
finally:
sys.stdout = stdout
return strout.getvalue()
[docs]def run_driver(prob):
"""
Call `run_driver` on problem and capture output.
Parameters
----------
prob : Problem
An instance of Problem.
Returns
-------
bool
Failure flag; True if failed to converge, False is successful.
string
Output from calling `run_driver` on the Problem, captured from stdout.
"""
stdout = sys.stdout
strout = StringIO()
sys.stdout = strout
try:
failed = prob.run_driver()
finally:
sys.stdout = stdout
return failed, strout.getvalue()
[docs]@contextmanager
def printoptions(*args, **kwds):
"""
Context manager for setting numpy print options.
Set print options for the scope of the `with` block, and restore the old
options at the end. See `numpy.set_printoptions` for the full description of
available options. If any invalid options are specified, they will be ignored.
>>> with printoptions(precision=2):
... print(np.array([2.0])) / 3
[0.67]
The `as`-clause of the `with`-statement gives the current print options:
>>> with printoptions(precision=2) as opts:
... assert_equal(opts, np.get_printoptions())
Parameters
----------
*args : list
Variable-length argument list.
**kwds : dict
Arbitrary keyword arguments.
Yields
------
str or int
See Also
--------
set_printoptions : Set printing options.
get_printoptions : Get printing options.
"""
opts = np.get_printoptions()
# ignore any keyword args that are not valid in this version of numpy
# e.g. numpy <=1.13 does not have the 'floatmode' option
kw_opts = dict((key, val) for key, val in kwds.items() if key in opts)
try:
np.set_printoptions(*args, **kw_opts)
yield np.get_printoptions()
finally:
np.set_printoptions(**opts)
def _nothing():
yield None
[docs]def do_nothing_context():
"""
Do nothing.
Useful when you have a block of code that only requires a context manager sometimes,
and you don't want to repeat the context managed block.
Returns
-------
contextmanager
A do nothing context manager.
"""
return contextmanager(_nothing)()
[docs]def remove_whitespace(s, right=False, left=False):
"""
Remove white-space characters from the given string.
If neither right nor left is specified (the default),
then all white-space is removed.
Parameters
----------
s : str
The string to be modified.
right : bool
If True, remove white-space from the end of the string.
left : bool
If True, remove white-space from the beginning of the string.
Returns
-------
str
The string with white-space removed.
"""
if not left and not right:
return re.sub(r"\s+", "", s, flags=re.UNICODE)
elif right and left:
return re.sub(r"^\s+|\s+$", "", s, flags=re.UNICODE)
elif right:
return re.sub(r"\s+$", "", s, flags=re.UNICODE)
else: # left
return re.sub(r"^\s+", "", s, flags=re.UNICODE)
_badtab = r'`~@#$%^&*()[]{}-+=|\/?<>,.:;'
_transtab = str.maketrans(_badtab, '_' * len(_badtab))
[docs]def str2valid_python_name(s):
"""
Translate a given string into a valid python variable name.
Parameters
----------
s : str
The string to be translated.
Returns
-------
str
The valid python name string.
"""
return s.translate(_transtab)
_container_classes = (list, tuple, set)
[docs]def make_serializable(o):
"""
Recursively convert numpy types to native types for JSON serialization.
This function should NOT be passed into json.dump or json.dumps as the 'default' arg.
Parameters
----------
o : object
The object to be converted.
Returns
-------
object
The converted object.
"""
if isinstance(o, _container_classes):
return [make_serializable(item) for item in o]
elif isinstance(o, dict):
s_key = [make_serializable_key(item) for item in o.keys()]
s_val = [make_serializable(item) for item in o.values()]
return dict(zip(s_key, s_val))
elif isinstance(o, np.ndarray):
return o.tolist()
elif isinstance(o, np.number):
return o.item()
elif isinstance(o, (str, float, int)):
return o
elif isinstance(o, bool) or isinstance(o, complex):
return str(o)
elif hasattr(o, '__dict__'):
try:
return o.to_json()
except AttributeError:
return o.__class__.__name__
else:
return o
[docs]def make_serializable_key(o):
"""
Recursively convert numpy types to native types for JSON serialization.
This function is for making serizializable dictionary keys, so no containers.
This function should NOT be passed into json.dump or json.dumps as the 'default' arg.
Parameters
----------
o : object
The object to be converted.
Returns
-------
object
The converted object.
"""
if isinstance(o, str):
return o
elif isinstance(o, np.number):
return o.item()
elif hasattr(o, '__dict__'):
return o.__class__.__name__
else:
return str(o)
[docs]def default_noraise(o):
"""
Try to convert some extra types during JSON serialization.
This is intended to be passed to json.dump or json.dumps as the 'default' arg. It will
attempt to convert values if possible, but if no conversion works, will return
'unserializable object (<type>)' instead of raising a TypeError.
Parameters
----------
o : object
The object to be converted.
Returns
-------
object
The converted object.
"""
if isinstance(o, _container_classes):
return [default_noraise(item) for item in o]
elif isinstance(o, dict):
s_key = [make_serializable_key(item) for item in o.keys()]
s_val = [default_noraise(item) for item in o.values()]
return dict(zip(s_key, s_val))
elif isinstance(o, np.ndarray):
return o.tolist()
elif isinstance(o, np.number):
return o.item()
elif isinstance(o, (str, float, int)):
return o
elif isinstance(o, bool) or isinstance(o, complex):
return str(o)
elif hasattr(o, '__dict__'):
return o.__class__.__name__
elif o is None:
return None
else:
return f"unserializable object ({type(o).__name__})"
[docs]def make_set(str_data, name=None):
"""
Construct a set containing the specified character strings.
Parameters
----------
str_data : None, str, or list of strs
Character string(s) to be included in the set.
name : str, optional
A name to be used in error messages.
Returns
-------
set
A set of character strings.
"""
if not str_data:
return set()
elif isinstance(str_data, str):
return {str_data}
elif isinstance(str_data, (set, list)):
for item in str_data:
if not isinstance(item, str):
typ = type(item).__name__
msg = f"Items in tags should be of type string, but type '{typ}' was found."
raise TypeError(msg)
if isinstance(str_data, set):
return str_data
elif isinstance(str_data, list):
return set(str_data)
elif name:
raise TypeError("The {} argument should be str, set, or list: {}".format(name, str_data))
else:
raise TypeError("The argument should be str, set, or list: {}".format(str_data))
[docs]def match_includes_excludes(name, includes=None, excludes=None):
"""
Check to see if the variable names pass through the includes and excludes filter.
Parameters
----------
name : str
Name to be checked for match.
includes : iter of str or None
Glob patterns for name to include in the filtering. None, the default, means
include all.
excludes : iter of str or None
Glob patterns for name to exclude in the filtering.
Returns
-------
bool
Return True if the name passes through the filtering of includes and excludes.
"""
# Process excludes
if excludes is not None:
for pattern in excludes:
if fnmatchcase(name, pattern):
return False
# Process includes
if includes is None:
return True
else:
for pattern in includes:
if fnmatchcase(name, pattern):
return True
return False
[docs]def match_prom_or_abs(name, prom_name, includes=None, excludes=None):
"""
Check to see if the variable names pass through the includes and excludes filter.
Parameters
----------
name : str
Unpromoted variable name to be checked for match.
prom_name : str
Promoted variable name to be checked for match.
includes : iter of str or None
Glob patterns for name to include in the filtering. None, the default, means
to include all.
excludes : iter of str or None
Glob patterns for name to exclude in the filtering.
Returns
-------
bool
Return True if the name passes through the filtering of includes and excludes.
"""
diff = name != prom_name
# Process excludes
if excludes is not None:
for pattern in excludes:
if fnmatchcase(name, pattern) or (diff and fnmatchcase(prom_name, pattern)):
return False
# Process includes
if includes is None:
return True
else:
for pattern in includes:
if fnmatchcase(name, pattern) or (diff and fnmatchcase(prom_name, pattern)):
return True
return False
_falsey = {'0', 'false', 'no', 'off', 'none', ''}
[docs]def is_truthy(s):
"""
Return True if the given string is 'truthy'.
Parameters
----------
s : str
The name string being tested.
Returns
-------
bool
True if the specified string is 'truthy'.
"""
return s.lower() not in _falsey
[docs]def env_truthy(env_var):
"""
Return True if the given environment variable is 'truthy'.
Parameters
----------
env_var : str
The name of the environment variable.
Returns
-------
bool
True if the specified environment variable is 'truthy'.
"""
return is_truthy(os.environ.get(env_var, ''))
[docs]def common_subpath(pathnames):
"""
Return the common dotted subpath found in all of the given dotted pathnames.
Parameters
----------
pathnames : iter of str
Dotted pathnames of systems.
Returns
-------
str
Common dotted subpath. Returns '' if no common subpath is found.
"""
if len(pathnames) == 1:
return pathnames[0]
if pathnames:
npaths = len(pathnames)
splits = [p.split('.') for p in pathnames]
minlen = np.min([len(s) for s in splits])
for common_loc in range(minlen):
p0 = splits[0][common_loc]
for i in range(1, npaths):
if p0 != splits[i][common_loc]:
break
else:
continue
break
else:
common_loc += 1
return '.'.join(splits[0][:common_loc])
return ''
def _is_slicer_op(indices):
"""
Check if an indexer contains a slice or ellipsis operator.
Parameters
----------
indices : ndarray
Indices to check.
Returns
-------
bool
Returns True if indices contains a colon or ellipsis operator.
"""
if isinstance(indices, tuple):
return any(isinstance(i, slice) or i is ... for i in indices)
return isinstance(indices, slice)
def _src_name_iter(proms):
"""
Yield keys from proms with promoted input names converted to source names.
Parameters
----------
proms : dict
Original dict with some promoted paths.
Yields
------
str
source pathname name
"""
for meta in proms.values():
yield meta['source']
def _src_or_alias_name(meta):
if 'alias' in meta:
alias = meta['alias']
if alias:
return alias
return meta['source']
def _src_or_alias_item_iter(proms):
"""
Yield items from proms with promoted input names converted to source or alias names.
Parameters
----------
proms : dict
Original dict with some promoted paths.
Yields
------
tuple
src_or_alias_name, metadata
"""
for name, meta in proms.items():
if 'alias' in meta and meta['alias'] is not None:
yield meta['alias'], meta
elif meta['source'] is not None:
yield meta['source'], meta
else:
yield name, meta
def _src_or_alias_dict(prom_dict):
"""
Convert a dict with promoted input names into one with source or alias names.
Parameters
----------
prom_dict : dict
Original dict with some promoted paths.
Returns
-------
dict
New dict with source pathnames or alias names.
"""
return {name: meta for name, meta in _src_or_alias_item_iter(prom_dict)}
[docs]def convert_src_inds(parent_src_inds, parent_src_shape, my_src_inds, my_src_shape):
"""
Compute lower level src_indices based on parent src_indices.
Parameters
----------
parent_src_inds : ndarray
Parent src_indices.
parent_src_shape : tuple
Shape of source expected by parent.
my_src_inds : ndarray or fancy index
Src_indices at the current system level, before conversion.
my_src_shape : tuple
Expected source shape at the current system level.
Returns
-------
ndarray
Final src_indices based on those of the parent.
"""
if parent_src_inds is None:
return my_src_inds
elif my_src_inds is None:
return parent_src_inds
if my_src_inds._flat_src:
return parent_src_inds.shaped_array(flat=True)[my_src_inds.flat()]
else:
return parent_src_inds.shaped_array(flat=False).reshape(my_src_shape)[my_src_inds()]
[docs]def shape2tuple(shape):
"""
Return shape as a tuple.
Parameters
----------
shape : int or tuple
The given shape.
Returns
-------
tuple or None
The shape as a tuple or None if shape is None.
"""
if isinstance(shape, tuple):
return shape
elif isinstance(shape, int):
return (shape,)
elif shape is None:
return shape
else:
try:
return tuple(shape)
except TypeError:
if not isinstance(shape, Integral):
raise TypeError(f"{type(shape).__name__} is not a valid shape type.")
return (shape,)
[docs]def get_connection_owner(system, tgt):
"""
Return (owner, promoted_src, promoted_tgt) for the given connected target.
Note : this is not speedy. It's intended for use only in error messages.
Parameters
----------
system : System
Any System. The search always goes from the model level down.
tgt : str
Absolute pathname of the target variable.
Returns
-------
tuple
(owning group, promoted source name, promoted target name).
"""
from openmdao.core.group import Group
model = system._problem_meta['model_ref']()
src = model._conn_global_abs_in2out[tgt]
abs2prom = model._var_allprocs_abs2prom
if src in abs2prom['output'] and tgt in abs2prom['input'][tgt]:
if abs2prom['input'][tgt] != abs2prom['output'][src]:
# connection is explicit
for g in model.system_iter(include_self=True, recurse=True, typ=Group):
if g._manual_connections:
tprom = g._var_allprocs_abs2prom['input'][tgt]
if tprom in g._manual_connections:
return g, g._var_allprocs_abs2prom['output'][src], tprom
return system, src, tgt
[docs]def wing_dbg():
"""
Make import of wingdbstub contingent on value of WING_DBG environment variable.
Also will import wingdbstub from the WINGHOME directory.
"""
if env_truthy('WING_DBG'):
import sys
import os
save = sys.path
new = sys.path[:] + [os.environ['WINGHOME']]
sys.path = new
try:
import wingdbstub
finally:
sys.path = save
[docs]class LocalRangeIterable(object):
"""
Iterable object yielding local indices while iterating over local or distributed vars.
The number of iterations for a distributed variable will be the full distributed size of the
variable but None will be returned for any indices that are not local to the given rank.
Parameters
----------
system : System
Containing System.
vname : str
Name of the variable.
use_vec_offset : bool
If True, return indices for the given variable within its vector, else just return
indices within the variable itself, i.e. range(var_size).
Attributes
----------
_inds : ndarray
Variable indices (unused for distributed variables).
_dist_size : int
Full size of distributed variable.
_start : int
Starting index of distributed variable on this rank.
_end : int
Last index + 1 of distributed variable on this rank.
_offset : int
Offset of this variable into the local vector,.
_iter : method
The iteration method used.
"""
[docs] def __init__(self, system, vname, use_vec_offset=True):
"""
Initialize the iterator.
"""
self._dist_size = 0
abs2meta = system._var_allprocs_abs2meta['output']
if vname in abs2meta:
sizes = system._var_sizes['output']
slices = system._outputs.get_slice_dict()
else:
abs2meta = system._var_allprocs_abs2meta['input']
sizes = system._var_sizes['input']
slices = system._inputs.get_slice_dict()
if abs2meta[vname]['distributed']:
var_idx = system._var_allprocs_abs2idx[vname]
rank = system.comm.rank
self._offset = np.sum(sizes[rank, :var_idx]) if use_vec_offset else 0
self._iter = self._dist_iter
self._start = np.sum(sizes[:rank, var_idx])
self._end = self._start + sizes[rank, var_idx]
self._dist_size = np.sum(sizes[:, var_idx])
else:
self._iter = self._serial_iter
if use_vec_offset:
self._inds = range(slices[vname].start, slices[vname].stop)
else:
self._inds = range(slices[vname].stop - slices[vname].start)
def _serial_iter(self):
"""
Iterate over a local non-distributed variable.
Yields
------
int
Variable index.
"""
yield from self._inds
def _dist_iter(self):
"""
Iterate over a distributed variable.
Yields
------
int or None
Variable index or None if index is not local to this rank.
"""
start = self._start
end = self._end
for i in range(self._dist_size):
if i >= start and i < end:
yield i - start + self._offset
else:
yield None
[docs] def __iter__(self):
"""
Return an iterator.
Returns
-------
iterator
An iterator over our indices.
"""
return self._iter()
[docs]def make_traceback():
"""
Create a traceback for use later with an exception.
The traceback will begin at the stack frame *above* the caller of make_traceback.
Returns
-------
traceback
The newly constructed traceback.
"""
finfo = getouterframes(currentframe())[2]
return types.TracebackType(None, finfo.frame, finfo.frame.f_lasti, finfo.frame.f_lineno)
