@ -147,7 +147,7 @@ class TexBookRenderer(Renderer):
def _get_variables(parameter, user_config):
'''Get the default value for the parameter, according to the language.
'''
schema = parameter.get('schema', {}).copy()
schema = parameter.get('schema', {})
data = utils.DictOfDict(parameter.get('default', {}))
data.update(user_config)