Python: FP in py/modification-of-default-value when modification is guarded by check of value

[s0]

As reported here: https://discuss.lgtm.com/t/false-positive-for-default-value-causing-early-return/1923

In this example: https://lgtm.com/projects/g/sympy/sympy/snapshot/190c7facbe879630c849b79962159f6b37459048/files/sympy/codegen/array_utils.py?sort=name&dir=ASC&mode=heatmap the mutation only occurs when a condition is met that is never true for the default value. As the default value is [], not [] will always be true when no parameter is passed in, so the default value will never me modified.