---
Γ := rules "expr"
  expr := rules "expr" "subtract" "expr"
    expr := rules "expr" "add" "expr"
      expr := rules "int"
        int := lexemes "INT"
          INT "1" (1, 1)
      add := lexemes "+"
        + "+" (1, 3)
      expr := rules "expr" "divide" "expr"
        expr := rules "expr" "multiply" "expr"
          expr := rules "int"
            int := lexemes "INT"
              INT "2" (1, 5)
          multiply := lexemes "*"
            * "*" (1, 7)
          expr := rules "int"
            int := lexemes "INT"
              INT "3" (1, 9)
        divide := lexemes "/"
          / "/" (1, 11)
        expr := rules "int"
          int := lexemes "INT"
            INT "6" (1, 13)
    subtract := lexemes "-"
      - "-" (1, 15)
    expr := rules "int"
      int := lexemes "INT"
        INT "7" (1, 17)