code: public static Optional<? extends DockerfileStatement> createFromLine(String cmd) {
          if (cmd.trim().isEmpty() || cmd.startsWith("#")) {
              return Optional.absent();
          }
  
          Optional<? extends DockerfileStatement> line;
  
          line = Add.create(cmd);
  
          if (line.isPresent()) {
              return line;
          }
  
          line = Env.create(cmd);
  
          if (line.isPresent()) {
              return line;
          }
  
          return Optional.of(new OtherLine(cmd));
  
      }
docs: Return a dockerfile statement