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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 cd(self, dir_p):
 """Change the current directory level. in dir_p of type str The name of the directory to go in. return progress of type :class:`IProgress` Progress object to track the operation completion. """

        if not isinstance(dir_p, basestring):
            raise TypeError("dir_p can only be an instance of type basestring")
        progress = self._call("cd",
                     in_p=[dir_p])
        progress = IProgress(progress)
        return progress