A map based on a B-Tree.
| BTreeMap | 
 A map based on a B-Tree.  | 
| IntoIter | 
 An owning iterator over the entries of a   | 
| Iter | 
 An iterator over the entries of a   | 
| IterMut | 
 A mutable iterator over the entries of a   | 
| Keys | 
 An iterator over the keys of a   | 
| OccupiedEntry | 
 A view into an occupied entry in a   | 
| Range | 
 An iterator over a sub-range of entries in a   | 
| RangeMut | 
 A mutable iterator over a sub-range of entries in a   | 
| VacantEntry | 
 A view into a vacant entry in a   | 
| Values | 
 An iterator over the values of a   | 
| ValuesMut | 
 A mutable iterator over the values of a   | 
| DrainFilter | 
Experimental An iterator produced by calling   | 
| IntoKeys | 
Experimental An owning iterator over the keys of a   | 
| IntoValues | 
Experimental An owning iterator over the values of a   | 
| Entry | 
 A view into a single entry in a map, which may either be vacant or occupied.  | 
    © 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
    https://doc.rust-lang.org/std/collections/btree_map/index.html