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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 scan(self, search_path=None):
 """Scan `search_path` for distributions usable in this environment Any distributions found are added to the environment. `search_path` should be a sequence of ``sys.path`` items. If not supplied, ``sys.path`` is used. Only distributions conforming to the platform/python version defined at initialization are added. """

        if search_path is None:
            search_path = sys.path

        for item in search_path:
            for dist in find_distributions(item):
                self.add(dist)