I copied CS Dojo's code but mine doesn't work

I'm fairly new to learning Python and I've been watching CS Dojo's tutorials for absolute beginners.
There's a video about solving sample problems from CodingBat with this particular problem, "String-2 double_char" text

I simply copied CS Dojo's solution in the video but mine doesn't seem to work.

Here's the problem from CodingBat: String-2 double_char

Given a string, return a string where for every char in the original, there are two chars.

For example,

`double_char('The') → 'TThhee'

double_char('AAbb') → 'AAAAbbbb'

double_char('Hi-There') → 'HHii--TThheerree'`

Here's the code:

`def double_char(str):
    to_return = ""
    for i in (str):
     to_return += i * 2
     return to_return`

when I run the code, it just returns the first character of str.

For example,
double_char("hello") only returns 'hh' instead of 'hheelloo'

You're returning from your function after only one iteration of str
Note: Untested code

Try changing this

def double_char(str):
    to_return = ""
    for i in (str):
     to_return += i * 2
     return to_return

to

def double_char(str):
    to_return = ""
    for i in (str):
     to_return += i * 2
     return to_return