code: public static Vec UUIDToStringVec(Vec src) {
      if( !src.isUUID() ) throw new H2OIllegalArgumentException("UUIDToStringVec() conversion only works on UUID columns");
      Vec res = new MRTask() {
        @Override public void map(Chunk chk, NewChunk newChk) {
          if (chk instanceof C0DChunk) { // all NAs
            for (int i=0; i < chk._len; i++)
              newChk.addNA();
          } else {
            for (int i=0; i < chk._len; i++) {
              if (!chk.isNA(i))
                newChk.addStr(PrettyPrint.UUID(chk.at16l(i), chk.at16h(i)));
              else
                newChk.addNA();
            }
          }
        }
      }.doAll(Vec.T_STR,src).outputFrame().anyVec();
      assert res != null;
      return res;
    }
docs: Create a new {@link Vec} of string values from a UUID {@link Vec}.
  
  String {@link Vec} is the standard hexadecimal representations of a UUID.
  
  @param src a UUID {@link Vec}
  @return a string {@link Vec}