Ruby: looping over content of an array or hash twice ?

Hi guys,

I'm working my way through the Odin Project's Ruby Building Block exercise and am currently stuck at Caesar Cypher

Here's the code:

def caesar_cipher(string, interval)
  cipherlist = []
  cipherlist = string.split()
  cipherlist.each do |word|
    word.each do |letter|
      print letter
    end
  end

end  

caesar_cipher("What a string!", 5) "Bmfy f xywnsl!"

Since I'm currently more familiar with Python than with Ruby, I tend to approach things with that point of view. For instance in Python it is possible to do the following:

cipherlist = ["What", "a", "string!"]
for word in cipherlist;
    for letter in word:
        print letter

This would result in an output that displays every single letter of the array on a single line. The printing is just a test and I plan to convert every single letter in that inner loop to an integer and then add a value (the second argument passed to the caesar_cipher function) to it, after which I will plug everything back into a different array and solve the problem. I just can't seem to figure out how to do this in Ruby. (without cheating and looking at other people's solution) Any feedback is welcome! Thanks in advance.