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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 append(self, item):
 """Appends a `Monomer to the `Polymer`. Notes ----- Does not update labelling. """

        if isinstance(item, Monomer):
            self._monomers.append(item)
        else:
            raise TypeError(
                'Only Monomer objects can be appended to an Polymer.')
        return