import inspect

x,y,z = 1,2,3

def retrieve_name(var):
    callers_local_vars = inspect.currentframe().f_back.f_locals.items()
    return [var_name for var_name, var_val in callers_local_vars if var_val is var]
    
def mod_retrieve_name(var):
    callers_local_vars = inspect.currentframe().f_back.f_back.f_locals.items()
    return [var_name for var_name, var_val in callers_local_vars if var_val is var]

def foo(bar):
	print retrieve_name(bar)
	print mod_retrieve_name(bar)

foo(x)