Constant VALUE_SENT 

const VALUE_SENT: usize = 0b00010;

Indicates that a value has been stored in the channel’s inner UnsafeCell.

Safety

This bit controls which side of the channel is permitted to access the UnsafeCell. If it is set, the UnsafeCell may ONLY be accessed by the receiver. If this bit is NOT set, the UnsafeCell may ONLY be accessed by the sender.