docs: def from_coordinates(cls, coordinates):
          """Creates a `Primitive` from a list of coordinates."""
          prim = cls()
          for coord in coordinates:
              pm = PseudoMonomer(ampal_parent=prim)
              pa = PseudoAtom(coord, ampal_parent=pm)
              pm.atoms = OrderedDict([('CA', pa)])
              prim.append(pm)
          prim.relabel_all()
          return prim