Error

def checkio(line):

return "-".join([i for i in line.split("-") if i])

if name == 'main': assert checkio(u'I---like--python') == "I-like-python", 'Example'

When i run this i get an error, but it should work! So whats the problem? The error is called like this "DjCenter...". And i also get infinite loading mark in right corner of webpage.