def symmetry(self):
        """
        Check whether a mesh has rotational symmetry.

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

        Returns
        -----------
        symmetry: None         No rotational symmetry
                  'radial'     Symmetric around an axis
                  'spherical'  Symmetric around a point