COMMENT Algol68 has unusual comments COMMENT
BEGIN
  PROC isprime = (INT n) BOOL:
  BEGIN
    IF n < 2 THEN FALSE
    ELSE
      BOOL prime := TRUE;
      FOR i FROM 2 TO ENTIER sqrt(n) WHILE prime DO
        IF n MOD i = 0 THEN
          prime := FALSE
        FI
      OD;
      prime
    FI
  END;

  print((isprime(17), newline))
END
