Check OS and Python Environment

check_environment.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""Check environments for an environmental variable value."""
import os

def check_environment(env_var, default=None):
    """Check environments for an environmental variable."""
    def boolify(var):
        if isinstance(default, bool):
            if var in [0, '0', 'FALSE', 'False', 'false', 'F', 'f']:
                return False
            if var in [1, '1', 'TRUE', 'True', 'true', 'T', 't']:
                return True
            raise TypeError(f'Unable to evaluate expected boolean: {env_var}')

    if env_var in os.environ:
        return_var = os.environ[env_var]
    elif env_var in globals():
        return_var = globals()[env_var]
    elif env_var in locals():
        return_var = locals()[env_var]
    else:
        return default
    if isinstance(default, bool) and not isinstance(return_var, bool):
        return boolify(return_var)
    if isinstance(default, int) and not isinstance(return_var, int):
        return int(return_var)
    if isinstance(default, float) and not isinstance(return_var, float):
        return float(return_var)
    return return_var

common usage is to have it as a seperate file, e.g. check_environment.py and then to use from check_environment import check_environment as ce to use a shorthand notion within other files.