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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 Dump(self, key = None):
 """ Using the standard Python pretty printer, return the contents of the scons build environment as a string. If the key passed in is anything other than None, then that will be used as an index into the build environment dictionary and whatever is found there will be fed into the pretty printer. Note that this key is case sensitive. """

        import pprint
        pp = pprint.PrettyPrinter(indent=2)
        if key:
            dict = self.Dictionary(key)
        else:
            dict = self.Dictionary()
        return pp.pformat(dict)