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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 instance():
 """Return an PyVabamorf instance. It returns the previously initialized instance or creates a new one if nothing exists. Also creates new instance in case the process has been forked. """

        if not hasattr(Vabamorf, 'pid') or Vabamorf.pid != os.getpid():
            Vabamorf.pid = os.getpid()
            Vabamorf.morf = Vabamorf()
        return Vabamorf.morf