This function can be used to check for three common problems in
networks: disconnected components, dangle nodes and close nodes. When a
network has disconnected components, this means that several unconnected
graphs are composing the overall network. This can be caused by topological
errors in the dataset. Dangle nodes are nodes connected to only one other
node. This type of node can be normal at the border of a network, but can
also be caused by topological errors. Close nodes are nodes that are not
coincident, but so close that they probably should be coincident.