The problem in my hand requires me to take a set of actions on a very large data frame df_1. This set of actions results in a second data frame df_2, and from this second data frame, I have multiple downstream tasks, task_1, task_2 ...  By default, these tasks will repeat the computation between df_1 and df_2. Is there a way to force evaluation at df_2 so that I don't need to repeat the same costly calculations again and again. I know I could save df_2 to force the evaluation, but wonder if there is another way to avoid writing and reading? Thanks!