def parent_function():
    y=10
    def child_function():
        print y
    child_function()

def receiving_function(f):
    f()

def parent_function():
    y=10
    def child_function():
        print y
    receiving_function(child_function)

>>> def parent_function():
...    y=10
...    def child_function():
...        print y
...    child_function()

>>> print y
Traceback (most recent call last):
  File "<interactive input>", line 1, in <module>
NameError: name 'y' is not defined

def func1():
y=30
def func2():
    print y
func2()

def func2():
    print y
def func1():
    y=30
    func2()