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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 PrependENVPath(self, name, newpath, envname = 'ENV', sep = os.pathsep, delete_existing=1):
 """Prepend path elements to the path 'name' in the 'ENV' dictionary for this environment. Will only add any particular path once, and will normpath and normcase all paths to help assure this. This can also handle the case where the env variable is a list instead of a string. If delete_existing is 0, a newpath which is already in the path will not be moved to the front (it will be left where it is). """


        orig = ''
        if envname in self._dict and name in self._dict[envname]:
            orig = self._dict[envname][name]

        nv = SCons.Util.PrependPath(orig, newpath, sep, delete_existing,
                                    canonicalize=self._canonicalize)

        if envname not in self._dict:
            self._dict[envname] = {}

        self._dict[envname][name] = nv