def is_array_type(rtype):
    """
    Test to see if return type parameter is a NumPy array.

    :param str rtype: Return type parameter.

    :return: *True* if return type parameter is a NumPy array, *False* if not.
    :rtype: bool
    """
    if rtype.lower() in ['ndarray', 'array', 'arr', 'np', 'a']:
        return True
    return False