Very headache questions

Question

I have seen the code as bellow (in the Python lesson of Sololearn):

def decor(func):
def wrap(): #Question1: Why we have to add a function of wrap() inside the function of decor()
print("============")
func()
print("============")
return wrap #Question2: Why we have to add a return here, what's this exact meaning, and why we can't just write: "return" ?

def print_text():
print("Hello world!")

a=decor(print_text)
a() #Question3: Why we can't just put "print(a)" here ? And why we have to put "()" after "a" ?

>>>>OUTPUT:
============
Hello world!
============

I have 3 questions:
Question1: Why we have to add a function of wrap() inside the function of decor()
Question2: Why we have to add a return at end of loop, what's this exact meaning, and why we can't just write: "return" ?
Question3: Why we can't just put "print(a)" at end ? And why we have to put "()" after "a" ?

Answer 1

Not so very headache answers

Answer 1: It's just an implementation and not really necessary. You can directly write contents of wrap function in the decor without writing nested function.
def decor(func):
print("========")
func()
print("========")

Answer 2: It's just to return warp function whenever decor is called so that you can call whatever is returned by decor function.

Answer 3: decor is returning a function which is being stored in a and so now a is a function.
print(a) will print the memory address of a. And why we've to put () after a? 'cause that's the syntax to call a function in Python.