fn last_checkpoint(&self) -> Height {
        let height = self.height();

        self.checkpoints
            .iter()
            .rev()
            .map(|(h, _)| *h)
            .find(|h| *h <= height)
            .unwrap_or(0)
    }
/// Get the height of the last checkpoint block.
Get the height of the last checkpoint block.
Get the height of the last checkpoint block .
fn last_checkpoint(&self) -> Height {
        let height = self.height();
        self.checkpoints
            .iter()
            .rev()
            .map(|(h, _)| *h)
            .find(|h| *h <= height)
            .unwrap_or(0)
    }
fn last_checkpoint ( & self ) -> Height { let height = self . height ( ) ; self . checkpoints . iter ( ) . rev ( ) . map ( | ( h , _ ) | * h ) . find ( | h | * h <= height ) . unwrap_or ( 0 ) }
Get the height of the last checkpoint block.
Get the height of the last checkpoint block .
&self