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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 require(self, entity_type, attribute_name=None):
 """ The intent parser should require an entity of the provided type. Args: entity_type(str):
 an entity type attribute_name(str):
 the name of the attribute on the parsed intent. Defaults to match entity_type. Returns: self: to continue modifications. """

        if not attribute_name:
            attribute_name = entity_type
        self.requires += [(entity_type, attribute_name)]
        return self