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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def extend(self, schema):
 """ Extend a structured schema by another. For example extending ``tuple<rstring id, timestamp ts, float64 value>`` with ``tuple<float32 score>`` results in ``tuple<rstring id, timestamp ts, float64 value, float32 score>``. Args: schema(StreamSchema):
 Schema to extend this schema by. Returns: StreamSchema: New schema that is an extension of this schema. """

        if self._spl_type:
           raise TypeError("Not supported for declared SPL types")
        base = self.schema()
        extends = schema.schema()
        new_schema = base[:-1] + ',' + extends[6:]
        return StreamSchema(new_schema)