@classmethod
def load(cls, filename, format='turtle', uri=None):
    """
        Load a collection from a file designated by its filename.

        If no URI for the collection is provided, we scan the graph to find
        the first ContextCollection in it. In there isn't any, the collection
        will load all available nif:Context in the graph.
        """
    with open(filename, 'r') as f:
        return cls.loads(f.read(), format=format, uri=uri)
