Getting the extension of a file

#last extension

filename = "google.com.py.txt.exe.zip.html"
filename2 = "www.google.com/index.phps"

def get_last_ext(filename):
    filenameb = filename[::-1]
    try:
        only_last_ext = (filenameb[:filenameb.index('.')])[::-1]
    except:
        only_last_ext = ""
    return only_last_ext

def get_last_ext2(filename):
    if '.' in filename:
        return filename[filename.index('.')+1:].split('.')[-1]
    return ""

print get_last_ext(filename)
print get_last_ext2(filename2)