def scan_rate_formatter(scan_rate):
    """
    Format the IDL table 'SCAN_RAT' column.
    
    In IDL at least, the scan rate column has a very particular format (0.0000 for cases 
    where there is no scan being done, left-aligned). There's no good one-step way of 
    doing that formatting in python, so here's what we're stuck with.
    
    Parameters
    ----------
    scan_rate : float
        The scan rate to format
    
    Returns
    -------
    scan_rate_str : str
        The scan rate, formatted as a four-decimal-place floating point, and left-aligned.
    """
    scan_rate_str = "{:6.4f}".format(scan_rate)
    return "{:<9}".format(scan_rate_str)