code: def tag_secondary_structure(self, force=False):
          
          for polymer in self._molecules:
              if polymer.molecule_type == 'protein':
                  polymer.tag_secondary_structure(force=force)
          return
docs: Tags each `Monomer` in the `Assembly` with it's secondary structure.
  
          Notes
          -----
          DSSP must be available to call. Check by running
          `isambard.external_programs.dssp.test_dssp`. If DSSP is not
          available, please follow instruction here to add it:
          https://github.com/woolfson-group/isambard#external-programs
  
          For more information on DSSP see [1].
  
          References
          ----------
          .. [1] Kabsch W, Sander C (1983) "Dictionary of protein 
             secondary structure: pattern recognition of hydrogen-bonded
             and geometrical features", Biopolymers, 22, 2577-637.
  
          Parameters
          ----------
          force : bool, optional
              If True the tag will be run even if `Monomers` are already tagged