pandas create a column with space based on the length of another column

Question

I want to create a new column based on length.

test = pd.DataFrame({"col1": [7,5,3]})
test['space_word'] =  f"{' ' * (test['col1'])} : left blank"

However, got error:

UFuncTypeError: ufunc 'multiply' did not contain a loop with signature matching types (dtype('<U21'), dtype('<U21')) -> dtype('<U21')

The desired output should be:

col1   space_word
   7           : left blank   
   5         : left blank
   3       : left blank

Solved:
Using transform()

test['space_word'] =  test.col1.transform(lambda x: f"check {' ' * x} : left blank")

   col1                  space_word
0     7  check         : left blank
1     5    check       : left blank
2     3      check     : left blank