Merge #418

418: Add a stability specification to the docs for unique and unique_by r=jswrenn a=mulkieran



Co-authored-by: mulhern <[email protected]>

Author: bors[bot]

src/lib.rs

@@ -1021,6 +1021,10 @@ pub trait Itertools : Iterator {
     /// Clones of visited elements are stored in a hash set in the
     /// iterator.
     ///
+    /// The iterator is stable, returning the non-duplicate items in the order
+    /// in which they occur in the adapted iterator. In a set of duplicate
+    /// items, the first item encountered is the item retained.
+    ///
     /// ```
     /// use itertools::Itertools;
     ///
@@ -1043,6 +1047,10 @@ pub trait Itertools : Iterator {
     /// with the keying function `f` by hash and equality.
     /// The keys are stored in a hash set in the iterator.
     ///
+    /// The iterator is stable, returning the non-duplicate items in the order
+    /// in which they occur in the adapted iterator. In a set of duplicate
+    /// items, the first item encountered is the item retained.
+    ///
     /// ```
     /// use itertools::Itertools;
     ///