input: Write a python function to convert a Roman numeral to an integer using the given class.
  ```python
  assert Roman_int("III").get_integer() == 3
  assert Roman_int("IV").get_integer() == 4
  assert Roman_int("IX").get_integer() == 9
  assert Roman_int("LVIII").get_integer() == 58
  assert Roman_int("MCMXCIV").get_integer() == 1994
output: class Roman_int:
      def __init__(self, roman):
          self.roman = roman
  
      def get_integer(self):
          roman_values = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
          integer_value = 0
          prev_value = 0
  
          for char in reversed(self.roman):
              current_value = roman_values[char]
              if current_value < prev_value:
                  integer_value -= current_value
              else:
                  integer_value += current_value
              prev_value = current_value
  
          return integer_value