getting global variables from dictionary

[icarus]

global_vars.py has the global variables
set_var.py changes one of the values on the global variables (don't
close it or terminate)
get_var.py retrieves the recently value changed (triggered right after
set_var.py above)

Problem: get_var.py retrieves the old value, the built-in one but not
the recently changed value in set_var.py.

What am I doing wrong?

----global_vars.py---
#!/usr/bin/python

class Variables :
	def __init__(self) :
		self.var_dict = {"username": "original username"}


---set_var.py ---
#!/usr/bin/python

import time
import global_vars

global_vars.Variables().var_dict["username"] = "new username"
time.sleep(10)   #give enough time to trigger get_var.py


---get_var.py ---
#!/usr/bin/python
import global_vars
print global_vars.Variables().var_dict.get("username")