pub fn is_closed(&self) -> bool {
        match self {
            Sender::Bounded(tx) => tx.is_closed(),
            Sender::Unbounded(tx) => tx.is_closed(),
        }
    }
/// Check if there is an existing receiver for this channel.
Check if there is an existing receiver for this channel.
Check if there is an existing receiver for this channel .
pub fn is_closed(&self) -> bool {
        match self {
            Sender::Bounded(tx) => tx.is_closed(),
            Sender::Unbounded(tx) => tx.is_closed(),
        }
    }
pub fn is_closed ( & self ) -> bool { match self { Sender :: Bounded ( tx ) => tx . is_closed ( ) , Sender :: Unbounded ( tx ) => tx . is_closed ( ) , } }
Check if there is an existing receiver for this channel.
Check if there is an existing receiver for this channel .
&self