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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 merge(self, resolvable, packages, parent=None):
 """Add a resolvable and its resolved packages."""

    self.__tuples.append(_ResolvedPackages(resolvable, OrderedSet(packages),
                                           parent, resolvable.is_constraint))
    self._check()