Python get filename suffix

Python day 25:

When i was younger, I only dealt with latex, docx, pdf files. Since i started blogging, i use a lot more files such as jpg, peg, mov4, ipynb, py, md, sas, r , HTML.
Sometimes, it is a bit difficult to organize the files.
Today we are going to make a small python program to fetch the suffix. 

Little Goal: Use python to fetch the filename suffix.

yibo.gif

def suffix(filename, has_dot=False):
    pos=filename.rfind(".")
    if 0< pos <len(filename) -1:
        index= pos if has_dot else pos +1
        return filename [index:]
    else:
        return " "

suffix("yibo.gif")
'gif'

yibo.jpg

suffix("yibo.jpg")
'jpg'