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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 setup_top(self):
 """Create top-level elements of the hybrid schema."""

        self.top_grammar = SchemaNode("grammar")
        self.top_grammar.attr = {
            "xmlns": "http://relaxng.org/ns/structure/1.0",
            "datatypeLibrary": "http://www.w3.org/2001/XMLSchema-datatypes"}
        self.tree = SchemaNode("start")