def fn_string_join(context, text, separator=''):
    """
    http://www.w3.org/TR/xpath-functions/#func-string-join
    Returns a string created by concatenating the members of the
    text sequence using separator.

    :param context: Parent DOM context
        :type context: EtreeElement
    :param text: matches xpath results
        :type text: list[str]
    :param separator:
        :type separator: str
    :rtype: str
    """
    del context
    return separator.join(text)
