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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 add_entry(self, entry):
 """Add a path item to ``.entries``, finding any distributions on it ``find_distributions(entry, True)`` is used to find distributions corresponding to the path entry, and they are added. `entry` is always appended to ``.entries``, even if it is already present. (This is because ``sys.path`` can contain the same value more than once, and the ``.entries`` of the ``sys.path`` WorkingSet should always equal ``sys.path``.) """

        self.entry_keys.setdefault(entry, [])
        self.entries.append(entry)
        for dist in find_distributions(entry, True):
            self.add(dist, entry, False)