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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 simplify(self):
 """Simplify the Expr."""

        d = defaultdict(float)
        for term in self.terms:
            term = term.simplify()
            d[term.ops] += term.coeff
        return Expr.from_terms_iter(
            Term.from_ops_iter(k, d[k]) for k in sorted(d, key=repr) if d[k])