Note: koan 53 requires a particular chain syntax.

Note: koan 53 requires a particular chain syntax.

Using a more recent chain syntax, _.chain(collection), will cause errors.
Koan 53 requires the original syntax : _(collection).chain

The more recent chain syntax was added more than 4 years ago,
and causes confusion when otherwise correct code produces errors.
Adding a note to koan 53 should remove this source of confusion
for users familiar with the newer underscore _.chain() syntax.

Same as Issue #64 on mrdavidlaing upstream repo.

reference notes: javascript-koans uses underscore v 1.1.6 from Apr 2011

newer chain syntax was added in v 1.2.3 on 30 Dec 2011 as jashkenas/underscore@62c814d9fee214c19cf29695ded2eaab6bbaf0f8 fix #408

current underscore library is v 1.8.3