PySkein contains a simple stream cipher based on Skein:
>>> import skein
>>> sc = skein.StreamCipher(b"secret")
>>> x = sc.encrypt(b"squeamish ossifrage")
>>> x
b'\x94!\xc5\xbfM\xb5%{\x96qPw\x7f\x16]\xf3\x1cEc'
>>> sc = skein.StreamCipher(b"secret")
>>> sc.decrypt(x)
b'squeamish ossifrage'