code coverage tests:

1. int
    $s[1]
    $i(^s.int[])
    1.1 ^i.double(2)
    1.2 ^i.dec(1) $i
    1.3 ^i.inc(1) $i
    1.4 ^i.mul(2) $i

2. double
    $d(1.1)
    2.1 ^d.double(2)

3. bool
    $b(true)
    3.1 ^b.double(2)
    3.2 ^if(^b.bool(false)){true}{false}

4. inet
    4.1 ^try-catch{ ^inet:aton[1.1.1.300] }
    4.2 ^try-catch{ ^inet:aton[a.b.c.d] }

    4.5 ^try-catch{ ^inet:ip2name[$empty] }
    4.6 ^try-catch{ ^inet:ip2name[ip; $.no-such-option[] ] }
    4.7 ^try-catch{ ^inet:ip2name[ip; $.ipv[invalid] ] }
    4.8 ^try-catch{ ^inet:ip2name[1.1.1.300] }
    4.9 ^try-catch{ ^inet:ip2name[1.1.1.1; $.ipv[6] ] }

    4.11 ^try-catch{ ^inet:name2ip[$empty] }
    4.12 ^try-catch{ ^inet:name2ip[name; $.no-such-option[] ] }
    4.13 ^try-catch{ ^inet:name2ip[no-such-domain.артлебедев.рф; $.ipv[6] ] }
    4.14 ^inet:name2ip[test.артлебедев.рф; $.ipv[6] ]

5. math
    5.1 ^math:random(1)
    5.2 ^try-catch{ ^math:random(1e10) }

    5.4 ^try-catch{ ^math:digest[shaX;123] }
    5.5 ^try-catch{ ^math:digest[sha1;123; $.format[unknown] ] }
    5.6 ^try-catch{ ^math:digest[sha1;123; $.no-such-option[] ] }

    5.10 ^try-catch{ ^math:convert[1](17;10) }
    5.11 ^try-catch{ ^math:convert[1](10;17) }
    5.12 ^math:convert[$empty](10;10)
    5.13 ^math:convert[+FF](16;10)

6. string
    6.1 ^try-catch{ $s[] ^s.int[] }
    6.2 ^try-catch{ $s[] ^s.double[] }
    6.3 ^try-catch{ $s[] ^s.bool[] }
    6.4 ^try-catch{ $s[] ^s.bool(bug) }
    6.5 ^try-catch{ $s[bug] ^s.bool[] }
    6.6 ^if(^s.bool(1)){true}{false}
    6.7 ^try-catch{ $s[s] ^s.pos[s](-1) }
    6.8 $s[a,b,c] ^json:string[^s.rsplit[,]; $.indent(true) ]
    6.9 $s[a,,b,c] ^json:string[^s.split[,,;rh]; $.indent(true) ]
    6.10 ^try-catch{  ^s.split[,;hv] }
    6.11 ^try-catch{ ^string:base64[anything; $.no-such-option[] ] }
    6.12 ^try-catch{ ^string:unescape[anything;anything; $.no-such-option[] ] }
    6.13 ^try-catch{ ^string:unescape[no-such-mode;anything] }
    6.14 ^try-catch{ ^string:unescape[js;any%20thing] }
    6.15 ^try-catch{ ^s.save[no-such-mode;file.txt] }

7. file
    7.1 ^try-catch{ ^file::base64[1;2] }
    7.2 ^try-catch{ ^file::base64{1}[2;3] }
    7.3 ^try-catch{ ^file::base64[text;fname.text;XXXXXX; $.no-such-option[] ] }
    7.4 ^try-catch{ ^file::base64[text;fname.text;XXXXXX; $.strict(true) ] }
    7.5 $f[^file::base64[text;fname.text;XXXXXX; $.content-type[strange] ]] ^json:string[$f]

    7.10 ^file:fullpath[/fname.txt]
    7.11 ^file:fullpath[fname.txt]

    7.15 ^try-catch{ ^file:list[.; $.stat(true) $.filter[.*] $.no-such-options[] ] }
    7.15 ^try-catch{ ^file:list[.; $.filter[ $.hash[] ] ] }