code: def IndexOfNth(s, value, n):
      
      remaining = n
      for i in xrange(0, len(s)):
          if s[i] == value:
              remaining -= 1
              if remaining == 0:
                  return i
      return -1
docs: Gets the index of Nth occurance of a given character in a string
  
      :param str s:
          Input string
      :param char value:
          Input char to be searched.
      :param int n:
          Nth occurrence of char to be searched.
  
      :return:
          Index of the Nth occurrence in the string.
      :rtype: int