How to make reappear the info of a function

Hi, 

When you are in INSERT mode and typing a function, e.g. `foo` with arguments `a` and `b`, i.e. `foo(a, b)`, then you have the pop-up info with information like: 

`foo(a: ..., b: ...)`

right after you press the parenthesis. But, if you press any button afterwards, e.g. return, then this pop-up goes away. How can one make it reappear? 