def eulerian_circuit(graph):

    trail = []

    for edge in graph:
        graph.sort()
        a,b = edge
        if not trail:
            trail.append(a)
            trail.append(b)
            graph.remove((a,b))
            print(graph)
        if a == trail[-1]:
            trail.append(b)
            graph.remove((a,b))
            print(graph)
        if not graph:
            return trail

    eulerian_circuit(graph)
    return trail,graph

eulerian_circuit([('a','b'), ('b','c'), ('a','f'), ('b','d'), ('d','f'), ('b','e'), ('e','g'), ('c','g'), ('f','g'), ('f','h'), ('g','h')])