[Tutor] What is the square brackets about?

[boB Stepp]

On Sat, Jan 16, 2016 at 2:33 PM, Alan Gauld <alan.gauld at btinternet.com> wrote:
> On 16/01/16 19:35, boB Stepp wrote:
>
>> And so on.  Until you (and I) can understand why the function produces
>> these outputs with the given values of loc and thing, then we cannot
>> claim we understand what is going on.  So I encourage you to
>> thoroughly explore your sample code!
>
> The function plumbs the depths of thing according to the indices
> supplies in loc. The shape of thing must match the length of loc.

The interesting part of this function for me was not the OP's original
questions, but why this particular use of a recursive function (Am I
using the proper terminology here?)?  Can someone provide a practical
use of this type of function where some more straightforward
searching/parsing approach would be ineffective?

-- 
boB