def get_string_expression(self, string_match_type=None):
pass<EOL>
Gets the regular expression of an acceptable string for the given string match type.

        arg:    string_match_type (osid.type.Type): a string match type
        return: (string) - the regular expression
        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.*