Loop

Loop steps are used to wait for a particular message.

A loop is written

#![allow(unused)]
fn main() {
repeat_step ->? stop_step
}

and will be matched when :

1. The step representing the stopping condition stop_step is matched, or

2. A message matching repeat_step is matched and then the same loop must be matched again

   #![allow(unused)]
   fn main() {
   repeat_step ->? stop_step
   }

For instance,

#![allow(unused)]
fn main() {
( 
  preendorse __ __ __ [__] ||
  endorse    __ __ __ [__] 
) 
->? propose __ __ __ [__]
}

waits for a proposal message and forwards any preendorsement and endorsement messages in the meantime.