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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 set_instrument(self, channel, instr, bank=0):
 """Set the channel to the instrument _instr_."""

        self.instr_event(channel, instr, bank)
        self.notify_listeners(self.MSG_INSTR, {'channel': int(channel),
            'instr': int(instr), 'bank': int(bank)})