code: public InlineMorph with(String line) {
          if (scriptBuilder.length() == 0) {
              appendBoilerplate(line);
          }
          scriptBuilder
                  .append(line)
                  .append("\n");
          return this;
      }
docs: Adds a line to the morph script.
  
  @param line the next line of the morph script
  @return a reference to {@code this} for continuation