>>>>> Should be compiled with: `./v -d ddd1=true -d ddd2=false`
>>>>> Note that ddd3 is not passed *on purpose*, to test the default .
===========================================================================
$d(ddd1, false) : true
$d(ddd1,  true) : true
------------------------------------------------------------
Checking $if with default false:
1 ddd1 is true
Checking $if with default true:
2 ddd1 is true
------------------------------------------------------------
Checking $if !$d(ddd1) with default false:
3 !ddd1 is false
Checking $if !$d() with default  true:
4 !ddd1 is false

===========================================================================
$d(ddd2, false) : false
$d(ddd2,  true) : false
------------------------------------------------------------
Checking $if with default false:
1 ddd2 is false
Checking $if with default true:
2 ddd2 is false
------------------------------------------------------------
Checking $if !$d() with default false:
3 !ddd2 is true
Checking $if !$d() with default  true:
4 !ddd2 is true

===========================================================================
$d(ddd3, false) : false
$d(ddd3,  true) : true
------------------------------------------------------------
Checking $if with default false:
1 ddd3 is false
Checking $if with default true:
2 ddd3 is true
------------------------------------------------------------
Checking $if !$d() with default false:
3 !ddd3 is true
Checking $if !$d() with default  true:
4 !ddd3 is false