def env_get_var_value(var_name):
    """Returns value for variable in os.environ

    Function throws AssertionError if variable is defined.
    Unit-test based python tests require certain input params
    to be set in environment, otherwise they can't be run
    """
    assert var_name in os.environ.keys(), "Please supply %s in environment" % var_name
    return os.environ[var_name]
dataset/ETHPy150Open byt3bl33d3r/pth-toolkit/lib/python2.7/site-packages/samba/tests/__init__.py/env_get_var_value/original