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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 get_namespaces_imported_by_route_io(self):
 # type: () -> typing.List[ApiNamespace] """ Returns a list of Namespace objects. A namespace is a member of this list if it is imported by the current namespace and has a data type from it referenced as an argument, result, or error of a route. Namespaces are in ASCII order by name. """

        namespace_data_types = sorted(self.get_route_io_data_types(),
                                      key=lambda dt: dt.name)
        referenced_namespaces = set()
        for data_type in namespace_data_types:
            if data_type.namespace != self:
                referenced_namespaces.add(data_type.namespace)
        return sorted(referenced_namespaces, key=lambda n: n.name)