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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 _field(self, *keys) -> Any: """Lookups given fields in _node, and if not found in _full_metadata. Raises KeyError if not found anywhere."""

        try:
            d = self._node
            for key in keys:
                d = d[key]
            return d
        except KeyError:
            d = self._full_metadata
            for key in keys:
                d = d[key]
            return d