Function safe_delegate_call_bool 

pub fn safe_delegate_call_bool(
    contract: [u8; 20],
    calldata: &[u8],
    gas: u64,
) -> bool

Check the codesize before invoking call, only reading a single byte at the location for a bool check. If the contract doesn’t return anything, then we assume everything went okay. If it does, then we check for true. We don’t return anything.