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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 hexa_word(data, separator = ' '):
 """ Convert binary data to a string of hexadecimal WORDs. @type data: str @param data: Binary data. @type separator: str @param separator: Separator between the hexadecimal representation of each WORD. @rtype: str @return: Hexadecimal representation. """

        if len(data) & 1 != 0:
            data += '\0'
        return separator.join( [ '%.4x' % struct.unpack('<H', data[i:i+2])[0] \
                                           for i in compat.xrange(0, len(data), 2) ] )