def env(*_vars, **kwargs):
    """Search for the first defined of possibly many env vars.

    Returns the first environment variable defined in vars, or
    returns the default defined in kwargs.

    """
    for v in _vars:
        value = os.environ.get(v, None)
        if value:
            return value
    return kwargs.get('default', '')
Search for the first defined of possibly many env vars.

    Returns the first environment variable defined in vars, or
    returns the default defined in kwargs.