in(node::Node, graph::DAG) = node in graph.nodes
in(edge::Edge, graph::DAG) = edge in graph.edges

function ==(n1::Node, n2::Node, g::DAG)
    if typeof(n1) != typeof(n2)
        return false
    end
    if !(n1 in g) || !(n2 in g)
        return false
    end

    return n1.task == n2.task && children(n1) == children(n2)
end