algo.return(algo.input) 
 

 ALGO.INPUT 
  Number or list 
   from which the expected result must be calculated 
   and returned through procedure ALGO.RETURN. 
  
 CALL.ARGS 
  Holds the list of arguments passed with CALL. 
  -> [arg1, ..., argN] 

 ALGO.RETURN(result) 
  End computation and 
   compare the calculated result 
   against the expected result. 
  Succeeds if there is a match; fails otherwise. 
  
 ALGO.RETURN(print_arg1, ..., print_argN) 
  End computation and 
   compare the concatenated print_args 
   against the expected result. 
  Succeeds if there is a match; fails otherwise. 
  
 CALL(&retvar1, ..., &retvarM, @modname, arg1, ..., argN) 
  Start executing module modname, copying N arguments and expecting M return values. 
  -> retvar: name of variable to hold the corresponding return value retval 
  -> modname: name of module to start executing 
  -> arg: value to be copied to the list CALL.ARGS 
  Alternative syntax: retvar1, ..., retvarM = CALL(@modname, arg1, ..., argN) 
  Note that recursive module calls are not allowed. 
  
 RETURN(retval1, ..., retvalM) 
  Return M values from the current module. 
  Resume execution at the next instruction of the corresponding CALL. 
  -> retval: value to be copied to the corresponding variable retvar