code: def coordinates(self):
          
          i = self._coordinates
          for name, _i in COORDINATES.items():
              if i==_i:
                  return name
          return i
docs: Get or set the internal coordinate system.
  
          Available coordinate systems are:
  
          - ``'jacobi'`` (default)
          - ``'democraticheliocentric'``
          - ``'whds'``