scope.txt

                           scope
a=10#scope of this variable is global we can access this variable anywhere in the program
def var():
   
    a=19#scope of this variable is local we can only access this variable inside the function
    print(a)

var()
print(a)


but if you want to update the value of global variable using function  we can use the keyword global so it will treat variable as global variable 

a=10
def var():
    global a
    a=19#now this a refer to global variable but now we cant use variable a as local
    print(a)

var()
print(a)
global() return the dict containing all global variable but we need only a so we mention the variable name as key this function give access to use global varible inside function and we can also use same name local varble 
global()['a']=78
if we update in this it does update the value of global variable it will create new block x
a=10#scope of this variable is global we can access this variable anywhere in the program
def var():
    x=globals()['a']
    x=20
    print(id(x),x)
    a=19#scope of this variable is local we can only access this variable inside the function
    print(a,id(a))
var()
print(a,id(a))
correct way
a=10#scope of this variable is global we can access this variable anywhere in the program
def var():
    x=globals()['a']=20#or globals()['a']=20
    print(id(x),x)
    a=19#scope of this variable is local we can only access this variable inside the function
    print(a,id(a))
var()
print(a,id(a))
now