Ayushmann Khurrana says his "Gulabo Sitabo" co-star Amitabh Bachchan is not a selfish actor, but a great collaborator.Ayushmann feels the child in Big B is still alive, and that makes him an amazing artist. "I had this notion that he is very serious as a person but he39s got this amazing childlike quality which sets him apart from his contemporaries, he is full of zeal and zest. The child in him is still alive so that makes him an amazing artist," Ayushmann said about working with Big B in "Gulabo Sitabo"."Also I thought he would be very strict on the set but on the contrary he was very jovial, very interactive and collaborative. I thought he would be immersed in his own lines but he is concerned about his co-actors also," he added. Ayushmann said that Big B helped him improvise his lines. "That was such an eye opener for me. I remember when I was marking my own lines in the script and he was like why are you marking your own lines you should mark my lines also. That goes to show he believes in the totality of the process, he39s not a selfish actor, he is a collaborator," he added. In the film scripted by Juhi Chaturvedi, Big B is seen as Mirza, landlord of an old dilapidated 39haveli39 in the heart of Lucknow, named Fatima Mahal, while Ayushmann is his shrewd tenant, Baankey. It is directed by Shoojit Sircar."Gulabo Sitabo", produced by Ronnie Lahiri and Sheel Kumar, is set to stream on Amazon Prime Video.