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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_disk_size(vm_, swap, linode_id):
    r'''
    Returns the size of of the root disk in MB.

    vm\_
        The VM to get the disk size for.
    '''
    disk_size = get_linode(kwargs={'linode_id': linode_id})['TOTALHD']
    return config.get_cloud_config_value(
        'disk_size', vm_, __opts__, default=disk_size - swap
    )