def get_vertices_from_edge_list(graph, edge_list):
node_set = set()<EOL>for edge_id in edge_list:<EOL><INDENT>edge = graph.get_edge(edge_id)<EOL>a, b = edge['<STR_LIT>']<EOL>node_set.add(a)<EOL>node_set.add(b)<EOL><DEDENT>return list(node_set)<EOL>
Transforms a list of edges into a list of the nodes those edges connect.
    Returns a list of nodes, or an empty list if given an empty list.