@lru_cache(maxsize=1)
def index(self) -> npt.NDArray[int]:
    "Retrieves an array of element indices\n\n        Parameters\n        ----------\n\n        Returns\n        -------\n        npt.NDArray\n            1D array of element indices.\n\n        Notes\n        -----\n        The result of this method is cached, so that multiple calls\n        to it won't result in multiple calculations. If the mesh\n        is modified and the cache is not properly clear the calls\n        to this method can result in invalid return values.\n        "
    return np.arange(len(self()))
Retrieves an array of element indices

Parameters
----------

Returns
-------
npt.NDArray
    1D array of element indices.

Notes
-----
The result of this method is cached, so that multiple calls
to it won't result in multiple calculations. If the mesh
is modified and the cache is not properly clear the calls
to this method can result in invalid return values.
@lru_cache(maxsize=1)
def index(self) -> npt.NDArray[int]:
    "Retrieves an array of element indices\n\n        Parameters\n        ----------\n\n        Returns\n        -------\n        npt.NDArray\n            1D array of element indices.\n\n        Notes\n        -----\n        The result of this method is cached, so that multiple calls\n        to it won't result in multiple calculations. If the mesh\n        is modified and the cache is not properly clear the calls\n        to this method can result in invalid return values.\n        "
    return np.arange(len(self()))