+ ///
+ /// # Time complexity
+ ///
+ /// The expected cost of `push`, averaged over every possible ordering of
+ /// the elements being pushed, and over a sufficiently large number of
+ /// pushes, is O(1). This is the most meaningful cost metric when pushing
+ /// elements that are *not* already in any sorted pattern.
+ ///
+ /// The time complexity degrades if elements are pushed in predominantly
+ /// ascending order. In the worst case, elements are pushed in ascending
+ /// sorted order and the amortized cost per push is O(log n) against a heap
+ /// containing *n* elements.
+ ///
+ /// The worst case cost of a *single* call to `push` is O(n). The worst case
+ /// occurs when capacity is exhausted and needs a resize. The resize cost
+ /// has been amortized in the previous figures.