'Create an url that refers to a specific version_number.'

def generate_href(self, version, path=None):

    if (version.find('v2.1') == 0):
        version_number = 'v2.1'
    else:
        version_number = 'v2'
    path = (path or '')
    return common.url_join(self.prefix, version_number, path)
