Promela and Model Description
9) Timeout and Assertion
    Timeout models a special condition that allows the process aborts waiting
    when no other statements within the system is executable.
    Assertion evaluate whether constraints are satisfied, just like in C/C++
ex1:proctype watchdog() {
do
   :: timeout -> guard!reset // timeout
od
     }
ex2: assert(any_boolean_condition) // assertion