code: def get_canonical_block_by_number(self, block_number: BlockNumber) -> BaseBlock:
          
          validate_uint256(block_number, title="Block Number")
          return self.get_block_by_hash(self.chaindb.get_canonical_block_hash(block_number))
docs: Returns the block with the given number in the canonical chain.
  
          Raises BlockNotFound if there's no block with the given number in the
          canonical chain.