ConvertGraph converts its input graph G to the format fmt. If G is of type GRAPHLN, the second argument is mandatory and must be one of graph6, sparse6, or bits. If G is not of type GRAPHLN, the second argument is optional, and can be either of the above formats as well as maple.

The input graph G can be a GraphTheory graph (GRAHLN), a networks graph, a graph6 or sparse6 representation of a graph (a string), or a bits representation of a graph (list of two integers).