def find_filter_class(filtername):
 if (filtername in FILTERS):
  return FILTERS[filtername]
 for (name, cls) in find_plugin_filters():
  if (name == filtername):
   return cls
 return None

def find_filter_class ( filtername ) : if ( filtername in FILTERS ) : return FILTERS [ filtername ] for ( name , cls ) in find_plugin_filters ( ) : if ( name == filtername ) : return cls return None
lookup a filter by name .