def codeChecker(wetland_type, modifiers):
    if modifiers is not None:
        modifiers = modifiers.split(', ')
        incorrect_modifiers = []
        match_dict = {'LOBA': ['ay', 'bv', 'fm', 'fn', 'gf', 'hs', 'il', 'mr', 'ox', 'sa', 'ag'],
                      'LOFP': [],
                      'LOFR': [],
                      'LEBA': [],
                      'LEFP': [],
                      'LEFR': [],
                      'TEBA': [],
                      'TEFL': [],
                      'TEFR': [],
                      'TESL': []}
        for modifier in modifiers:
            if modifier not in match_dict[wetland_type]:
                incorrect_modifiers.append(modifier)
        return(', '.join(incorrect_modifiers))
    else:
        return(None)