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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 _set_residue_map(self):
 """ map each residue to the corresponding molecule. """

        self.map_residue_to_mol = {}
        lookup = {}
        for idx, mol in enumerate(self.mols):
            if not mol.formula in lookup:
                mol.translate_sites(indices=range(len(mol)),
                                    vector=-mol.center_of_mass)
                lookup[mol.formula] = mol.copy()
            self.map_residue_to_mol["ml{}".format(idx + 1)] = lookup[mol.formula]