<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def union(self, *dstreams):
 """ Create a unified DStream from multiple DStreams of the same type and same slide duration. """

        if not dstreams:
            raise ValueError("should have at least one DStream to union")
        if len(dstreams) == 1:
            return dstreams[0]
        if len(set(s._jrdd_deserializer for s in dstreams)) > 1:
            raise ValueError("All DStreams should have same serializer")
        if len(set(s._slideDuration for s in dstreams)) > 1:
            raise ValueError("All DStreams should have same slide duration")
        cls = SparkContext._jvm.org.apache.spark.streaming.api.java.JavaDStream
        jdstreams = SparkContext._gateway.new_array(cls, len(dstreams))
        for i in range(0, len(dstreams)):
            jdstreams[i] = dstreams[i]._jdstream
        return DStream(self._jssc.union(jdstreams), self, dstreams[0]._jrdd_deserializer)