using shutil to move files with a unique extension

import os
import shutil
sourcepath='C:/Users/kevinconnell/Desktop/Test_Folder/'
sourcefiles = os.listdir(sourcepath)
destinationpath = 'C:/Users/kevinconnell/Desktop/Test_Folder/Archive'
for file in sourcefiles:
    if file.endswith('.png'):
        shutil.move(os.path.join(sourcepath,file), os.path.join(destinationpath,file))