def clean(inst, clean_level=None):
    """Provides data cleaning based upon clean_level.

    clean_level is set upon Instrument instantiation to
    one of the following:

    'Clean'
    'Dusty'
    'Dirty'
    'None'

    Routine is called by pysat, and not by the end user directly.

    Parameters
    -----------
    inst : (pysat.Instrument)
        Instrument class object, whose attribute clean_level is used to return
        the desired level of data selectivity.

    Returns
    --------
    Void : (NoneType)
        data in inst is modified in-place.

    Note
    ----
        Supports 'clean', 'dusty', 'dirty', 'none'

    """
    if clean_level != 'none':
        print("Cleaning actions for ICON MIGHTI aren't yet defined.")
    return
