docs: note that depth_first_search also works for Result.
diff --git a/src/visit/dfsvisit.rs b/src/visit/dfsvisit.rs
index 3acaf77..0b7af3f 100644
--- a/src/visit/dfsvisit.rs
+++ b/src/visit/dfsvisit.rs
@@ -141,18 +141,23 @@
/// and edge classification of each reachable edge. `visitor` is called for each
/// event, see [`DfsEvent`][de] for possible values.
///
-/// If the return value of the visitor is simply `()`, the visit runs until it
-/// is finished. If the return value is a `Control<B>`, it can be used to
-/// change the control flow of the search. `Control::Break` will stop
-/// the visit early, returning the contained value from the function.
+/// The return value should implement the trait `ControlFlow`, and can be used to change
+/// the control flow of the search.
+///
+/// `Control` Implements `ControlFlow` such that `Control::Continue` resumes the search.
+/// `Control::Break` will stop the visit early, returning the contained value.
/// `Control::Prune` will stop traversing any additional edges from the current
/// node and proceed immediately to the `Finish` event.
///
+/// There are implementations of `ControlFlow` for `()`, and `Result<C, E>` where
+/// `C: ControlFlow`. The implementation for `()` will continue until finished.
+/// For `Result`, upon encountering an `E` it will break, otherwise acting the same as `C`.
+///
/// ***Panics** if you attempt to prune a node from its `Finish` event.
///
/// [de]: enum.DfsEvent.html
///
-/// # Example
+/// # Example returning `Control`.
///
/// Find a path from vertex 0 to 5, and exit the visit as soon as we reach
/// the goal vertex.
@@ -194,6 +199,46 @@
/// path.reverse();
/// assert_eq!(&path, &[n(0), n(2), n(4), n(5)]);
/// ```
+///
+/// # Example returning a `Result`.
+/// ```
+/// use petgraph::graph::node_index as n;
+/// use petgraph::prelude::*;
+/// use petgraph::visit::depth_first_search;
+/// use petgraph::visit::{DfsEvent, Time};
+///
+/// let gr: Graph<(), ()> = Graph::from_edges(&[(0, 1), (1, 2), (1, 1), (2, 1)]);
+/// let start = n(0);
+/// let mut back_edges = 0;
+/// let mut discover_time = 0;
+/// // Stop the search, the first time a BackEdge is encountered.
+/// let result = depth_first_search(&gr, Some(start), |event| {
+/// match event {
+/// // In the cases where Ok(()) is returned,
+/// // Result falls back to the implementation of Control on the value ().
+/// // In the case of (), this is to always return Control::Continue.
+/// // continuing the search.
+/// DfsEvent::Discover(_, Time(t)) => {
+/// discover_time = t;
+/// Ok(())
+/// }
+/// DfsEvent::BackEdge(_, _) => {
+/// back_edges += 1;
+/// // the implementation of ControlFlow for Result,
+/// // treats this Err value as Continue::Break
+/// Err(event)
+/// }
+/// _ => Ok(()),
+/// }
+/// });
+///
+/// // Even though the graph has more than one cycle,
+/// // The number of back_edges visited by the search should always be 1.
+/// assert_eq!(back_edges, 1);
+/// println!("discover time:{:?}", discover_time);
+/// println!("number of backedges encountered: {}", back_edges);
+/// println!("back edge: {:?}", result);
+/// ```
pub fn depth_first_search<G, I, F, C>(graph: G, starts: I, mut visitor: F) -> C
where
G: IntoNeighbors + Visitable,
