This function is not part of the ERC721 standard.
It serves as an example of how to use the MRC721-internals functions to implement custom features.
Here we make use of the _update function from the MRC721-internals to burn a token.
Indeed, by calling _update with the zero address as a recipient, we are burning the token.
We also made sure that the burn feature is only callable by the owner of the token or an approved operator.
Indeed, the _update function will check if the caller is the owner of the token or an approved operator.
Remarks
This function is not part of the ERC721 standard. It serves as an example of how to use the MRC721-internals functions to implement custom features. Here we make use of the _update function from the MRC721-internals to burn a token. Indeed, by calling _update with the zero address as a recipient, we are burning the token.
We also made sure that the burn feature is only callable by the owner of the token or an approved operator. Indeed, the _update function will check if the caller is the owner of the token or an approved operator.