pe/lifetime/lifetime_coercion.html)
      8. [ **15.4.8.** Static ](../../scope/lifetime/static_lifetime.html)
      9. [ **15.4.9.** Elision ](../../scope/lifetime/elision.html)
  31. [ **16.** Traits ](../../trait.html) â± 
  32.     1. [ **16.1.** Derive ](../../trait/derive.html)
    2. [ **16.2.** Returning Traits with dyn ](../../trait/dyn.html)
    3. [ **16.3.** Operator Overloading ](../../trait/ops.html)
    4. [ **16.4.** Drop ](../../trait/drop.html)
    5. [ **16.5.** Iterators ](../../trait/iter.html)
    6. [ **16.6.** impl Trait ](../../trait/impl_trait.html)
    7. [ **16.7.** Clone ](../../trait/clone.html)
    8. [ **16.8.** Supertraits ](../../trait/supertraits.html)
    9. [ **16.9.** Disambiguating overlapping traits ](../../trait/disambiguating.html)
  33. [ **17.** macro_rules! ](../../macros.html) â± 
  34.     1. [ **17.1.** Syntax ](../../macros/syntax.html) â± 
    2.       1. [ **17.1.1.** Designators ](../../macros/designators.html)
      2. [ **17.1.2.** Overload ](../../macros/overload.html)
      3. [ **17.1.3.** Repeat ](../../macros/repeat.html)
    3. [ **17.2.** DRY (Don't Repeat Yourself) ](../../macros/dry.html)
    4. [ **17.3.** DSL (Domain Specific Languages) ](../../macros/dsl.html)
    5. [ **17.4.** Variadics ](../../macros/variadics.html)
  35. [ **18.** Error handling ](../../error.html) â± 
  36.     1. [ **18.1.** panic ](../../error/panic.html)
    2. [ **18.2.** abort & unwind ](../../error/abort_unwind.html)
    3. [ **18.3.** Option & unwrap ](../../error/option_unwrap.html) â± 
    4.       1. [ **18.3.1.** Unpacking options with ? ](../../error/option_unwrap/question_mark.html)
      2. [ **18.3.2.** Combinators: map ](../../error/option_unwrap/map.html)
      3. [ **18.3.3.** Combinators: and_then ](../../error/option_unwrap/and_then.html)
      4. [ **18.3.4.** Defaults: or, or_else, get_or_insert, 'get_or_insert_with` ](../../error/option_unwrap/defaults.html)
    5. [ **18.4.** Result ](../../error/result.html) â± 
    6.       1. [ **18.4.1.** map for Result ](../../error/result/result_map.html)
      2. [ **18.4.2.** aliases for Result ](../../error/result/result_alias.html)
      3. [ **18.4.3.** Early returns ](../../error/result/early_returns.html)
      4. [ **18.4.4.** Introducing ? ](../../error/result/enter_question_mark.html)
    7. [ **18.5.** Multiple error types ](../../error/multiple_error_types.html) â± 
    8.       1. [ **18.5.1.** Pulling Results out of Options ](../../error/multiple_error_types/option_result.html)
      2. [ **18.5.2.** Defining an error type ](../../error/multiple_error_types/define_error_type.html)
      3. [ **18.5.3.** Boxing errors ](../../error/multiple_error_types/boxing_errors.html)
      4. [ **18.5.4.** Other uses of ? ](../../error/multiple_error_types/reenter_question_mark.html)
      5. [ **18.5.5.** Wrapping errors ](../../error/multiple_error_types/wrap_error.html)
    9. [ **18.6.** Iterating over Results ](../../error/iter_result.html)
  37. [ **19.** Std library types ](../../std.html) â± 
  38.     1. [ **19.1.** Box, stack and heap ](../../std/box.html)
    2. [ **19.2.** Vectors ](../../std/vec.html)
    3. [ **19.3.** Strings ](../../std/str.html)
    4. [ **19.4.** Option ](../../std/option.html)
    5. [ **19.5.** Result ](../../std/result.html) â± 
    6.       1. [ **19.5.1.** ? ](../../std/result/question_mark.html)
    7. [ **19.6.** panic! ](../../std/panic.html)
    8. [ **19.7.** HashMap ](../../std/hash.html) â± 
    9.       1. [ **19.7.1.** Alternate/custom key types ](../../std/hash/alt_key_types.html)
      2. [ **19.7.2.** HashSet ](../../std/hash/hashset.html)
    10. [ **19.8.** Rc ](../../std/rc.html)
    11. [ **19.9.** Arc ](../../std/arc.html)
  39. [ **20.** Std misc ](../../std_misc.html) â± 
  40.     1. [ **20.1.** Threads ](../../std_misc/threads.html) â± 
    2.       1. [ **20.1.1.** Testcase: map-reduce ](../../std_misc/threads/testcase_mapreduce.html)
    3. [ **20.2.**