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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 get_nadir(self, channel=0) -> tuple: """Get the coordinates, in units, of the minimum in a channel. Parameters channel : int or str (optional) Channel. Default is 0. Returns ------- generator of numbers Coordinates in units for each axis. """

        # get channel
        if isinstance(channel, int):
            channel_index = channel
        elif isinstance(channel, str):
            channel_index = self.channel_names.index(channel)
        else:
            raise TypeError("channel: expected {int, str}, got %s" % type(channel))
        channel = self.channels[channel_index]
        # get indicies
        idx = channel.argmin()
        # finish
        return tuple(a[idx] for a in self._axes)