You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1, 2, 3 or 4 steps. In how many distinct ways can you climb to the top? Use a recursive method and then calculate the number of ways for 5, 10, 15 and 30 steps. 

 Use a recursive class method to reverse the characters of a string and then use it on the following strings: "California", "I want to reverse this string!". Hint: You may need to check the documentation of substring.