Closure python en lecture seule

gistfile1.py

# this works (like javascript)

def test(value): # functions that returns a function

    def closure(plus): # function got 'value' in a closure
        
        return value + plus

    return closure


func = test(5) # create a function that always add 5

print func(2)
# display 7

# But this doesn't work (but does ion JS):

def test(value):

    def closure(plus):
        
        value = value + plus # modify the closure

        return value

    return closure



func = test(5) 

print func(2)

# this trigger this weird error:

# UnboundLocalError                         
# Traceback (most recent call last)
# /home/kevin/<ipython-input-12-0f5d249a85b0> in <module>()
# ----> 1 test(5)(2)

# /home/kevin/<string> in closure(plus)

# UnboundLocalError: local variable 'value' referenced before assignment