def build_data(_data, kwds):
    """
    Returns property data dict, regardless of how it was entered.

    :param _data: Optional property data dict.
    :type _data: dict

    :param kwds: Optional property data keyword pairs. 
    :type kwds: dict

    :rtype: dict

    """
    # Doing this rather than defaulting the _data arg to a mutable value
    data = {} if _data is None else _data
    data.update(kwds)
    return data