docs: def close_monomers(self, group, cutoff=4.0):
          """Returns a list of Monomers from within a cut off distance of the Monomer
  
          Parameters
          ----------
          group: BaseAmpal or Subclass
              Group to be search for Monomers that are close to this Monomer.
          cutoff: float
              Distance cut off.
  
          Returns
          -------
          nearby_residues: [Monomers]
              List of Monomers within cut off distance.
          """
          nearby_residues = []
          for self_atom in self.atoms.values():
              nearby_atoms = group.is_within(cutoff, self_atom)
              for res_atom in nearby_atoms:
                  if res_atom.parent not in nearby_residues:
                      nearby_residues.append(res_atom.parent)
          return nearby_residues