Open IDLE, new file. 1 line: 
value = 1
Save file as updatevalue.py

new file, 2 lines:
import updatevalue
print updatevalue.value
Save file as update.py

Run module update.py
result in Python shell:
1

open updatevalue.py, change line into:
value = 2
Save
Run module update.py
result in Python shell:
1
	
close any combination of IDLE windows,( but not all)
Run module update.py
result in Python shell:
1

close all windows and restart IDLE
Run module update.py
result in Python shell:
2