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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_coalesce(devname, **kwargs):
    '''
    Changes the coalescing settings of the specified network device

    CLI Example:

    .. code-block:: bash

        salt '*' ethtool.set_coalesce <devname> [adaptive_rx=on|off] [adaptive_tx=on|off] [rx_usecs=N] [rx_frames=N]
            [rx_usecs_irq=N] [rx_frames_irq=N] [tx_usecs=N] [tx_frames=N] [tx_usecs_irq=N] [tx_frames_irq=N]
            [stats_block_usecs=N] [pkt_rate_low=N] [rx_usecs_low=N] [rx_frames_low=N] [tx_usecs_low=N] [tx_frames_low=N]
            [pkt_rate_high=N] [rx_usecs_high=N] [rx_frames_high=N] [tx_usecs_high=N] [tx_frames_high=N]
            [sample_interval=N]
    '''

    try:
        coalesce = ethtool.get_coalesce(devname)
    except IOError:
        log.error('Interrupt coalescing not supported on %s', devname)
        return 'Not supported'

    changed = False
    for param, value in kwargs.items():
        if param in ethtool_coalesce_map:
            param = ethtool_coalesce_map[param]
            if param in coalesce:
                if coalesce[param] != value:
                    coalesce[param] = value
                    changed = True

    try:
        if changed:
            ethtool.set_coalesce(devname, coalesce)
        return show_coalesce(devname)
    except IOError:
        log.error('Invalid coalesce arguments on %s: %s', devname, coalesce)
        return 'Invalid arguments'