The Truth, the Whole Truth, and Nothing But the Truth.

truth.py

import distutils.utils

def truth(s):
    """ :return True|False|None: truth(iness) value.
        :param object s: a value from os.environ.get().
    """ 
    if s in (True, False, None):
        return s
    if isinstance(s, int):
        if s > 0:
            return True
        return False
    if isinstance(s, float):
        if s > 0:
            return True
        return False
    return bool(distutils.util.strtobool(s))