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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 gridfs_namespace(self, plain_src_ns):
 """Given a plain source namespace, return the corresponding plain target namespace if this namespace is a gridfs collection. """

        namespace = self.lookup(plain_src_ns)
        if namespace and namespace.gridfs:
            return namespace.dest_name
        return None