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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 is_protein_package(self):
        '''Return true if this package is an Amino Acid alignment package, otherwise
        False i.e. it is a nucleotide package. Cache the result for speed.

        '''
        if not hasattr(self, '_is_protein_package'):
            self._is_protein_package = GraftMPackageVersion3.graftm_package_is_protein(self)
        return self._is_protein_package