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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 read_moc(self, filename):
 """Read a file into the current running MOC object. If the running MOC object has not yet been created, then it is created by reading the file, which will import the MOC metadata. Otherwise the metadata are not imported. """


        if self.moc is None:
            self.moc = MOC(filename=filename)

        else:
            self.moc.read(filename)