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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 _set_named_args(self, **kv):
 """ Set a named parameter in the query. The named field must exist in the query itself. :param kv: Key-Value pairs representing values within the query. These values should be stripped of their leading `$` identifier. """

        for k in kv:
            self._body['${0}'.format(k)] = kv[k]
        return self