Tags each monomer with side-chain dihedral angles

        force: bool, optional
            If `True` the tag will be run even if `Residues` are
            already tagged.

def tag_sidechain_dihedrals(self, force=False):
        """Tags each monomer with side-chain dihedral angles

        force: bool, optional
            If `True` the tag will be run even if `Residues` are
            already tagged.
        """
        tagged = ['chi_angles' in x.tags.keys() for x in self._monomers]
        if (not all(tagged)) or force:
            for monomer in self._monomers:
                chi_angles = measure_sidechain_torsion_angles(
                    monomer, verbose=False)
                monomer.tags['chi_angles'] = chi_angles
        return