code: def from_gromacs(cls, path, positions=None, forcefield=None, strict=True, **kwargs):
          
          if strict and positions is None:
              raise ValueError('Gromacs TOP files require initial positions.')
          box = kwargs.pop('box', None)
          top = GromacsTopFile(path, includeDir=forcefield, periodicBoxVectors=box)
          return cls(master=top, topology=top.topology, positions=positions, box=box,
                     path=path, **kwargs)
docs: Loads a topology from a Gromacs TOP file located at `path`.
  
          Additional root directory for parameters can be specified with `forcefield`.
  
          Arguments
          ---------
          path : str
              Path to a Gromacs TOP file
          positions : simtk.unit.Quantity
              Atomic positions
          forcefield : str, optional
              Root directory for parameter files