[MikroTik scripting] string replace

#strreplace
# 1 - where
# 2 - what
# 3 - with
:global strreplace do={
  :local l1 [:len $1];
  :local l2 [:len $2];
  :local l3 [:len $3];
  :local lr 0;
  :local i 0;
  :local k -1;
  :local r $1;
  :do {
    :set lr [:len $r];
    :set i [:find $r $2 $k];
    :if ($i != nil) do={
      :set r ([:pick $r -1 $i] . $3 . [:pick $r ($i + $l2) $lr]) ;
      :set k ($i + $l3 - 1);
    }
  } while=($i < $l1)
  :return $r;
}