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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def encipher(self,string):
 """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. """
           
        string = self.remove_punctuation(string)#,filter='[^'+self.key+']')
        ret = ''
        for c in range(0,len(string)):
            ret += self.encipher_char(string[c])
        return ret