In Langston Hughes, I Wonder as I Wander, page 397, we find a notice printed on Barcelona music hall programs in 1938:
JUST A MOMENT, COMRADE
The United Syndicate of Public Spectacles begs you to have the greatest respect for all the comrades you are going to see on stage. They are workers just as you are. DON’T DISTURB the show and spoil its performance. Take art as it should be taken.
The Joint Committee of CNT-UGT.