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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 _build_implicit_prefetches( self, model, prefetches, requirements ):
 """Build a prefetch dictionary based on internal requirements."""


        for source, remainder in six.iteritems(requirements):
            if not remainder or isinstance(remainder, six.string_types):
                # no further requirements to prefetch
                continue

            related_field = get_model_field(model, source)
            related_model = get_related_model(related_field)

            queryset = self._build_implicit_queryset(
                related_model,
                remainder
            ) if related_model else None

            prefetches[source] = self._create_prefetch(
                source,
                queryset
            )

        return prefetches