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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(self, request):
 """ Generate a payload for the given request. """

        payload = {}
        for field, gen in self._generators.items():
            value = None
            if callable(gen):
                value = gen(request)
            else:
                value = gen

            if value:
                payload[field] = value
        return payload