IPython on terminal doesn't show functions signature on parentheses opening

Question

Using IPython on my linux terminal (Debian), I would like to see the function signature (arguments and docstring) when I press ( after the function name, in a popup.

Notes:

• function_name? works.

• I'm sure that program actually sees the function data, since when I write pd.DataFrame(col<Tab> it autocompletes with columns=, an argument of pd.DataFrame.

• I already tried Tab and S-Tab without success.