docs: def unwrap(msmt):
      """Convert the value into the most basic representation that we can do
      math on: float if possible, then Uval, then Lval."""
  
      if np.isscalar(msmt):
          return float(msmt)
      if isinstance(msmt, (Uval, Lval)):
          return msmt
      if isinstance(msmt, Textual):
          return msmt.unwrap()
      raise ValueError('don\'t know how to treat %r as a measurement' % msmt)