How to use the decorator.get_tiers function in decorator

eb.set_type(results)
        
        # Compare the results of the low-level type detection to
        # that of the expectation and the assumption.
        if not expectation in (0, results):
            eb.reject = True
            err_mesg = "Extension type mismatch (expected %s, found %s)"
            err_mesg = err_mesg % (types[expectation], types[results])
            eb.warning(err_mesg)
        
        
    
    # ---- Begin Tiers ----
    
    # Iterate through each tier
    for tier in sorted(decorator.get_tiers()):
        
        print "Entering tier #%d" % tier
        
        # Iterate through each test of our detected type
        for test in decorator.run_tests(tier, eb.detected_type):
            # Pass in:
            # - Error Bundler
            # - Package listing
            # - A copy of the package itself
            test(eb, package_contents, p)
        
        # Return any errors at the end of the tier
        if eb.failed():
            return eb