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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 generate_func_code(self):
 """ Creates base code of validation function and calls helper for creating code by definition. """

        self.l('NoneType = type(None)')
        # Generate parts that are referenced and not yet generated
        while self._needed_validation_functions:
            # During generation of validation function, could be needed to generate
            # new one that is added again to `_needed_validation_functions`.
            # Therefore usage of while instead of for loop.
            uri, name = self._needed_validation_functions.popitem()
            self.generate_validation_function(uri, name)