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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 decrypt_ascii(self, ascii_string, key=None, digest="hex"):
 """ Receive ascii string and return decrypted data. Avaiable digests: hex: Hexadecimal base64: Base 64 hqx: hexbin4 """

        digests = {"hex": binascii.a2b_hex,
                   "base64": binascii.a2b_base64,
                   "hqx": binascii.a2b_hqx}
        digestor = digests.get(digest)
        if not digestor:
            TripleSecError(u"Digestor not supported.")

        binary_string = digestor(ascii_string)
        result = self.decrypt(binary_string, key)
        return result