docstring for my .py files does not work in Sage Notebook [UPD1]

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Hello! Sage 5.10, Linux Mint 15 Cinnamon.
I created new directory "pycode" in /home/andrei/
There is one file my_func.py in /home/andrei/pycode
The context of my_module.py:

import sage.all
def my_func(a, b, c):
"""
hello!
"""
return(a+b+c)

In Sage Notebook I do the next:

import sys # 1st cell
sys.path.append('/home/andrei/pycode/') # 2nd cell
import my_module # 3rd cell
my_module.my_func? # 4 cell

I don't see any docstring in Sage Notebook. Where is the error? Please help me. Thanks.

UPD1: I found the answer! :) First of all I turned off and then launched sage notebook. After that I saw my docstring. Then I use Action... --> Restart worksheet. Please explain me why shift+enter doesn't work for me. Thanks.