How to read from string until string becomes uppercase?

I’m trying to extract everything before the text becomes uppercase at the letter G, and none of the text that comes after.

string = 'abcdefGfecdab'

So the goal is to return ‘abcdef’.
I tried a for loop with a nested while loop

for a in string:
   while(a==a.lower()):
      print(a)

>Solution :

Don’t print, concatenate to a result string that you’ll return at the end.

You don’t need a while loop, you need an if statement to test the current character. And when the test fails, use break to exit the for loop.

result = ''
for a in string:
    if a.islower():
        result += a
    else:
        break
print(result)