I find students correctly infer what to do with "..." whereas they were afraid to touch "pass".

E.g, if I gave them this:

    def foo(x):
      ...  #add your implementation here
    
    def bar(x):
      pass #add your implementation here

I'd get back this:

    def foo(x):
      return x+1
      
    def bar(x):
      return x+1
      pass