def encipher(self,string):
string = self.remove_punctuation(string)<EOL>ret = '<STR_LIT>'<EOL>for c in range(<NUM_LIT:0>,len(string)):<EOL><INDENT>ret += self.encipher_char(string[c])<EOL><DEDENT>return ret<EOL>
Encipher string using Polybius square cipher according to initialised key.

        Example::

            ciphertext = Polybius('APCZWRLFBDKOTYUQGENHXMIVS',5,'MKSBU').encipher(plaintext)     

        :param string: The string to encipher.
        :returns: The enciphered string. The ciphertext will be twice the length of the plaintext.