text: # This program is implying encryption method in which each letter is replaced with another letter in a permanent shift.
  # In this program the shift is 13.
  # 
  # Implement a function that creates the dictionary: key = {'a':'n','b':'o'.....}
  # the key starts at 'a', reaches 'z'. and then starts at 'A' and finishes at 'Z'
  # the values are lower or upper case according to the key
  # implement encryption and decryption functions using 13 shift.
  # the function accepts a readable string and replaces letters according to the method.
  # also write a function that decrypts the string and returns it to normal.
  # try to decipher this: V NZ YRNEAVAT CLGUBA JVGU FUR PBQRF NPNQRZL!
  
  #function that creates the dictionary that shifts each letter 13 spots
  def shifting_13():
      #creating 2 strings of the alphabet that go on after "z" till "z" also gets shifted
      abc = "abcdefghijklmnopqrstuvwxyzabcdefghijklmn"
      ABC = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMN"
      dictionary_shifting_13 = {}
      #looping through all the alphabet
      for i in range(0,26):
          dictionary_shifting_13.update({abc[i]:ABC[i+13]})
          dictionary_shifting_13.update({ABC[i]:abc[i+13]})
      return dictionary_shifting_13
  
  
  #function that uses that dictionary and gets the desired letter for each letter in the string, and 
  # brings the value of that letter (key)
  
  def encryption(some_string):
      encrypted_list = []
      dictionary_shifting_13 = shifting_13()
      for letter in some_string:
          if dictionary_shifting_13.get(letter,'none') == 'none':
              encrypted_list.append(letter)
          else:
              encrypted_list.append(dictionary_shifting_13.get(letter))
      encrypted_string = " ".join(encrypted_list)
      return encrypted_list
  
  print(encryption("V NZ YRNEAVAT CLGUBA JVGU FUR PBQRF NPNQRZL!"))