docs: def int_to_str_digit(n):
      """
      Converts a positive integer, to a single string character.
      Where: 9 -> "9", 10 -> "A", 11 -> "B", 12 -> "C", ...etc
  
      Args:
          n(int): A positve integer number.
  
      Returns:
          The character representation of the input digit of value n (str).
      """
      # 0 - 9
      if n < 10:
          return str(n)
      # A - Z
      elif n < 36:
          return chr(n + 55)
      # a - z or higher
      else:
          return chr(n + 61)