hof: Removed unnecessary "if" in is_odd() definition.
Merge pull request #258 from orium/is_odd-minor

Removed unnecessary "if" in is_odd() definition.
hof: remove extern

Crate ‘num’ is not required to compile but breaks ‘Run’ button on
website
No more Vec::get() method in rust
Merge pull request #262 from vbuslov/master

hof: remove extern
Merge pull request #263 from AOrazaev/master

Fix example for vectors.
Fixed mut_iter() to iter_mut()
Fixed redundancies in struct patterns
Merge pull request #266 from GBGamer/fix-iter-mut

Fixed mut_iter() to iter_mut()
Merge pull request #267 from GBGamer/fix-for-13

Fixed redundancies in struct patterns
Fix the language in Lifetime's "grok" expression

The expression did not quite work in English. The following sentence was also missing a full-stop.
Merge pull request #271 from allenap/patch-1

lifetimes: Fix the language in "grok" expression