pub fn at_mut(&mut self, index: usize) -> Option<&mut Item> {
        if index < self.len() {
            Some(unsafe { &mut *(self.arena.at(ArenaIndex(index)) as *mut Item) })
        } else {
            None
        }
    }
/// Get a mutable reference to the item at `index`
Get a mutable reference to the item at `index`
Get a mutable reference to the item at ` index `
pub fn at_mut(&mut self, index: usize) -> Option<&mut Item> {
        if index < self.len() {
            Some(unsafe { &mut *(self.arena.at(ArenaIndex(index)) as *mut Item) })
        } else {
            None
        }
    }
pub fn at_mut ( & mut self , index : usize ) -> Option < & mut Item > { if index < self . len ( ) { Some ( unsafe { & mut * ( self . arena . at ( ArenaIndex ( index ) ) as * mut Item ) } ) } else { None } }
Get a mutable reference to the item at `index`
Get a mutable reference to the item at ` index `
&mut self
index
usize
&mut self
index
usize