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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 get_pltdotstr(self, **kws_usr):
 """Plot one GO header group in Grouper."""

        dotstrs = self.get_pltdotstrs(**kws_usr)
        assert len(dotstrs) == 1
        return dotstrs[0]