def check_type_and_size_of_param_list(param_list, expected_length):
    """
    Ensure that param_list is a list with the expected length. Raises a helpful
    ValueError if this is not the case.
    """
    try:
        assert isinstance(param_list, list)
        assert len(param_list) == expected_length
    except AssertionError:
        msg = "param_list must be a list containing {} elements."
        raise ValueError(msg.format(expected_length))

    return None