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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 _edit2(self, w):
 """ Returns a set of words with edit distance 2 from the given word """

        # Of all spelling errors, 99% is covered by edit distance 2.
        # Only keep candidates that are actually known words (20% speedup).
        return set(e2 for e1 in self._edit1(w) for e2 in self._edit1(e1) if e2 in self)