def valid_identifier(s):
    if isinstance(s, _strtypes):
        if not s or s[0].isdigit():
            return
        return s.replace(' ', '_').replace('.', '_').replace('-', '_')
    return s
Allows the overriding of the default extraction directory basename.
dataset/ETHPy150Open blaze/blaze/blaze/expr/expressions.py/valid_identifier--crossover with--dataset/ETHPy150Open devttys0/binwalk/src/binwalk/modules/extractor.py/Extractor.override_output_directory_basename