def available_color(G, vertex, color):
    """Returns True if color is available or not

    Parameters:
        G: a networkx graph with Graph Nodes
        vertex: the vertex number (int)
        color: the color to see if available
    Returns:
        available: True if color is available (boolean)
    """
    available = True
    for neighbor in G.neighbors(vertex):
        if G.nodes[neighbor]['node'].color == color:
            available = False
            break
    return available