pub fn title_to_number(title: String) -> i32 {
  let mut result = 0;

  for (index, character) in title.chars().rev().enumerate() {
    // Convert the character to a number and subtract 9 so A will equal 1.
    let number = character.to_digit(36).unwrap() - 9;

    let n = if index == 0 {
      number
    } else {
      26_u32.pow(index as u32) * number
    };

    result += n;
  }

  result as i32
}