Put a string in osx clipboard with Python

I used to store strings in files and then put the file content into clipboard by shell redirection, today I have found a better way:

teststring = "I am now in clipboard 3 !"
p = Popen(["pbcopy"], stdin=PIPE)
# p.communicate(input=teststring.encode(encoding='utf_8', errors='strict'))
p.communicate(input=teststring.encode())