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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 decipher(self,string):
 """Decipher string using FracMorse cipher according to initialised key. Example:: plaintext = FracMorse('ROUNDTABLECFGHIJKMPQSVWXYZ').decipher(ciphertext) :param string: The string to decipher. :returns: The enciphered string. """
                   
        string = string.upper()
        mapping = dict(zip(self.key,self.table))
        ptext = ""
        for i in string:
            ptext += mapping[i]
        return self.demorse(ptext)