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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 projection(self, plain_src_name):
 """Return the projection for the given source namespace."""

        mapped = self.lookup(plain_src_name)
        if not mapped:
            return None
        fields = mapped.include_fields or mapped.exclude_fields
        if fields:
            include = 1 if mapped.include_fields else 0
            return dict((field, include) for field in fields)
        return None