text: def cipher(text, shift, encrypt=True):
      """
      One of the simplest and most widely known encryption techniques. 
      
      Inputs
      ----------
      a single word/ words/ the text contains symbols/ a sentence
      
      Outputs
      -------
      For each letter in inputs, it is replaced by a letter some fixed number of positions down the alphabet.
      
      Examples
      --------
      >>> example = 'Apple'
      
      >>> encrypting = cipher(example, 1, )
      >>> print(encrypting)
      Bqqmf
      
      >>> decrypting = cipher(encrypting, 1, False)
      >>> print(decrypting)
      Apple
      """
  
      alphabet = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
      new_text = ''
      for c in text:
          index = alphabet.find(c)
          if index == -1:
              new_text += c
          else:
              new_index = index + shift if encrypt == True else index - shift
              new_index %= len(alphabet)
              new_text += alphabet[new_index:new_index+1]
      return new_text
  