<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _random_edge_iterator(graph, n_edges: int) -> Iterable[Tuple[BaseEntity, BaseEntity, int, Mapping]]: """Get a random set of edges from the graph and randomly samples a key from each. :type graph: pybel.BELGraph :param n_edges: Number of edges to randomly select from the given graph """

    edges = list(graph.edges())
    edge_sample = random.sample(edges, n_edges)
    for u, v in edge_sample:
        keys = list(graph[u][v])
        k = random.choice(keys)
        yield u, v, k, graph[u][v][k]