Add nested and/or filtering

I'd prefer a proper 'and' test, but that's a little tricky without structs,
which is a little tricky without a text import format..
On 8 Oct 2014 17:41, "Charles O'Farrell" <charles.ofarrell@ambiata.com>
wrote:

> and with one arg is a no-op (and so it's still an or with three values
> basically). Or at you asking why it parses?
> On 8 Oct 2014 17:38, "Ben Lever" <notifications@github.com> wrote:
>
>> In ivory-cli/src/test/bin/tests/window/input/dictionary.psv:
>>
>> > @@ -2,4 +2,4 @@ halibut:swiss_cheese|encoding=double|tombstone=T
>> >  halibut:cooldown|source=halibut:swiss_cheese|window=1 month|expression=count
>> >  halibut:latte|source=halibut:swiss_cheese|window=2 months|expression=count
>> >  filter:age|encoding=int
>> > -filter:adult|source=filter:age|expression=count|window=2 months|filter=or,18,19,20|tombstone=T
>> > +filter:adult|source=filter:age|expression=count|window=2 months|filter=or,(and,18),19,(and,20)|tombstone=T
>>
>> Is this an error scenario, or am I just not getting how the expressions
>> work?
>>
>> —
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>> <https://github.com/ambiata/ivory/pull/323/files#r18566048>.
>>
>