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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 Columnar Transposition cipher according to initialised key. Punctuation and whitespace are removed from the input. Example:: ciphertext = ColTrans('GERMAN').encipher(plaintext) :param string: The string to encipher. :returns: The enciphered string. """
                    
        string = self.remove_punctuation(string)    
        ret = ''
        ind = self.sortind(self.keyword)
        for i in range(len(self.keyword)):
            ret += string[ind.index(i)::len(self.keyword)]
        return ret