@abc.abstractmethod<EOL><INDENT>def get_string_expression(self, string_match_type):<DEDENT>
return<EOL>
Gets the regular expression of an acceptable string for the given string match type.

        :param string_match_type: a string match type
        :type string_match_type: ``osid.type.Type``
        :return: the regular expression
        :rtype: ``string``
        :raise: ``NullArgument`` -- ``string_match_type`` is ``null``
        :raise: ``IllegalState`` -- syntax is not a ``STRING``
        :raise: ``Unsupported`` -- ``supports_string_match_type(string_match_type`` ) is ``false``

        *compliance: mandatory -- This method must be implemented.*