def convert_to_ttl(self, value):
        ''' converts a value to the prefixed rdf ns equivalent. If not found
            returns the value as is.

        args:
            value: the value to convert
        '''

        parsed = self.parse_uri(value)

        try:
            rtn_val = "%s:%s" % (self.uri_dict[parsed[0]], parsed[1])
        except KeyError:
            rtn_val = self.iri(self.rpyhttp(value))

        return rtn_val
converts a value to the prefixed rdf ns equivalent. If not found
            returns the value as is.

        args:
            value: the value to convert