> filter: a'c
> filter: ''a' ''c
> filter: ""
+> # check operation when the condition modifies the 'value' variable
+> E
>
> map: ""
> map: a:b:c
> match: cdab
> Failed: "if" failed and "fail" requested
> match: cd[xyz]ab
+> # check for empty capture group
+> match: <>
>
> match_domain: yes
> match_domain: no
> rc=0
> 1!=2
> rc=0
+> abcd
+1234
+
+> rc=0
+> 2
+> rc=1
>
> # PRVS
>