code: def get_atoms(self, ligands=True, inc_alt_states=False):
          
          if ligands and self.ligands:
              monomers = self._monomers + self.ligands._monomers
          else:
              monomers = self._monomers
          atoms = itertools.chain(
              *(list(m.get_atoms(inc_alt_states=inc_alt_states)) for m in monomers))
          return atoms
docs: Flat list of all the Atoms in the Polymer.
  
          Parameters
          ----------
          inc_alt_states : bool
              If true atoms from alternate conformations are included rather
              than only the "active" states.
  
          Returns
          -------
          atoms : itertools.chain
              Returns an iterator of all the atoms. Convert to list if you
              require indexing.