/// Returns a mutable reference to the chunk section at the given
/// Y offset. The Y offset must be between 0 and 15, inclusive;
/// each Y offset value corresponds to 16 blocks vertically.
///
/// If this function returns `None`, the section is assumed
/// to be empty, meaning it consists only of air.
Returns a mutable reference to the chunk section at the given
Y offset. The Y offset must be between 0 and 15, inclusive;
each Y offset value corresponds to 16 blocks vertically.

If this function returns `None`, the section is assumed
to be empty, meaning it consists only of air.
Returns a mutable reference to the chunk section at the given Y offset . The Y offset must be between 0 and 15 inclusive ; each Y offset value corresponds to 16 blocks vertically . If this function returns ` None ` the section is assumed to be empty meaning it consists only of air .
pub fn section_mut(&mut self, index: usize) -> Option<&mut ChunkSection> {
        assert!(index < NUM_SECTIONS);
        self.modified = true;
        self.sections[index].as_mut()
    }
pub fn section_mut ( & mut self , index : usize ) -> Option < & mut ChunkSection > { assert ! ( index NUM_SECTIONS ) ; self . modified = true ; self . sections [ index ] . as_mut ( ) }
Returns a mutable reference to the chunk section at the given
Y offset.
Returns a mutable reference to the chunk section at the given Y offset .
&mut self
index
usize