code: def symmetry(self):
          
          symmetry, axis, section = inertia.radial_symmetry(self)
          self._cache['symmetry_axis'] = axis
          self._cache['symmetry_section'] = section
          return symmetry
docs: Check whether a mesh has rotational symmetry.
  
          Returns
          -----------
          symmetry: None         No rotational symmetry
                    'radial'     Symmetric around an axis
                    'spherical'  Symmetric around a point