---
chars := rules "chars" "char"
  chars := rules "chars" "char"
    chars := rules "chars" "char"
      chars := rules "chars" "char"
        chars := rules 
        char := lexemes "CHAR"
          CHAR "a" (1, 1)
      char := lexemes "CHAR"
        CHAR "b" (1, 2)
    char := lexemes "CHAR"
      CHAR "c" (1, 3)
  char := lexemes "CHAR"
    CHAR "d" (1, 4)