_ : Char< \t>+            # redefine whitespace to just tab and space

Factor : @{
    Int _                 # built-in 64-bit signed integer token
    '(' _ Expr ')' _
}

Term : @{
    Term '*' _ Factor     $1 * $4
    Term '/' _ Factor     $1 / $4
    Factor
}

Expr : @{
    Expr '+' _ Term       $1 + $4
    Expr '-' _ Term       $1 - $4
    Term
}

Expr _ print("= " + $1)   # gives some neat result output