input: def int_to_Roman(number: int) -> str:
      """ Convert a given number into its Roman form.
      >>> int_to_Roman(15)
      'XV'
      >>> int_to_Roman(45)
      'XLV'
      >>> int_to_Roman(99)
      'XCIX'
      >>> int_to_Roman(100)
      'C'
      >>> int_to_Roman(3999)
      'MMMCMXCIX'
      """
      
      val = [ 
          1000, 900, 500, 400, 
          100, 90, 50, 40,
          10, 9, 5, 4,
          1
          ] 
      syb = [ 
          "M", "CM", "D", "CD", 
          "C", "XC", "L", "XL", 
          "X", "IX", "V", "IV",
          "I"
          ] 
      roman_num = '' 
      i = 0
      while  number > 0:
          for_val = number // val[i]
          roman_num += syb[i] * for_val
          number -= val[i] * for_val
          i += 1
      return roman_num
output:     val = [ 
          1000, 900, 500, 400, 
          100, 90, 50, 40,
          10, 9, 5, 4,
          1
          ] 
      syb = [ 
          "M", "CM", "D", "CD", 
          "C", "XC", "L", "XL", 
          "X", "IX", "V", "IV",
          "I"
          ] 
      roman_num = '' 
      i = 0
      while  number > 0:
          for_val = number // val[i]
          roman_num += syb[i] * for_val
          number -= val[i] * for_val
          i += 1
      return roman_num