def nodes_menors_1(g, n):
    cjt_nm = set()
    for m in g.nodes:
        if m < n:
            cjt_nm.add(m)
    return cjt_nm

def nodes_menors_2(g, n):
    nm = filter(lambda m: m < n, g.nodes)
    cjt_nm = set(nm)
    return cjt_nm

def nodes_menors_3(g, n):
    cjt_nm = {m for m in g.nodes if m < n}
    return cjt_nm

# Tria la solució que vulguis provar
nodes_menors = nodes_menors_1
# nodes_menors = nodes_menors_2
# nodes_menors = nodes_menors_3