how can i right a program for giving me staras?

Question

A program that gets an input as int like n
if n>=3 it gives me a triangle of stars
for example when n=6 the out put is
*
**
***
****
*****
******
*****
****
***
**
*

Answer 1

banoo use stars(num) only
When you are using print inside a function and not returning any value, using print(stars(num)) returns none

Answer 2

for i in range(1,6+1):
print(i*"*")
for i in range(6-1,0,-1):
print(i*"*")

Answer 3

Abhay thanks for your help
I wrote this and it works but I dont understand why at the end it shows None
How can I avoid this?

def stars(n):
if n>=3:
for i in range(1,(n+1)):
print (i*"*")
for i in range((n-1),0,-1):
print(i*"*")
num=int(input("type a number:")
print(stars(num))

>>>
type a number:3
>>>
*
**
***
**
*
None