code: def add_quantities(d, coords=None, massE=0.511e6):
      '''
      Add physically interesting quantities to
      pext data.
  
      Parameters:
      -----------
        d      : pext array
  
      Keywords:
      ---------
        coords : sequence of positions for angle calculation. None
                 or by default, calculate no angles.
                 For 2D, takes the angle depending on the order passed,
                 so this can be used for left-handed coordinate systems
                 like LSP's xz.
        massE  : rest mass energy of particles.
      Returns a copy with the quantities appended.
      '''
      keys,items = zip(*calc_quantities(d,coords=coords,massE=massE).items());
      return rfn.rec_append_fields(
          d, keys, items)f add_quantities(d, coords=None, massE=0.511e6):
      '''
      Add physically interesting quantities to
      pext data.
  
      Parameters:
      -----------
        d      : pext array
  
      Keywords:
      ---------
        coords : sequence of positions for angle calculation. None
                 or by default, calculate no angles.
                 For 2D, takes the angle depending on the order passed,
                 so this can be used for left-handed coordinate systems
                 like LSP's xz.
        massE  : rest mass energy of particles.
      Returns a copy with the quantities appended.
      '''
      keys,items = zip(*calc_quantities(d,coords=coords,massE=massE).items());
      return rfn.rec_append_fields(
          d, keys, items);
docs: Add physically interesting quantities to
      pext data.
  
      Parameters:
      -----------
        d      : pext array
  
      Keywords:
      ---------
        coords : sequence of positions for angle calculation. None
                 or by default, calculate no angles.
                 For 2D, takes the angle depending on the order passed,
                 so this can be used for left-handed coordinate systems
                 like LSP's xz.
        massE  : rest mass energy of particles.
      Returns a copy with the quantities appended.