code: def encipher(self,string):
                          
          string = self.remove_punctuation(string)
          step1 = self.pb.encipher(string)
          evens = step1[::2]
          odds = step1[1::2]
          step2 = []
          for i in range(0,len(string),self.period):
              step2 += evens[i:int(i+self.period)]
              step2 += odds[i:int(i+self.period)]
          return self.pb.decipher(''.join(step2))
docs: Encipher string using Bifid cipher according to initialised key. Punctuation and whitespace
          are removed from the input.       
  
          Example::
  
              ciphertext = Bifid('phqgmeaylnofdxkrcvszwbuti',5).encipher(plaintext)     
  
          :param string: The string to encipher.
          :returns: The enciphered string.