def register_custom_supported_check(alias, f, plugin_agnostic=False):
 EXTENSION_SUPPORTED_CHECK_MAP[alias] = f
 if plugin_agnostic:
  _PLUGIN_AGNOSTIC_EXTENSIONS.add(alias)

def register_custom_supported_check ( alias , f , plugin_agnostic = False ) : EXTENSION_SUPPORTED_CHECK_MAP [ alias ] = f if plugin_agnostic : _PLUGIN_AGNOSTIC_EXTENSIONS . add ( alias )
register a custom function to determine if extension is supported .