code: private static String flattenImports(Set<String> imports) {
      StringBuilder sb = new StringBuilder();
  
      for (String import_: imports) {
        sb.append(import_).append("\n");
      }
  
      return sb.toString();
    }
docs: Takes a set of imports constructed with {@link #importString}, and produces a valid import block
  for use at the top of a typescript source file
  
  @param imports the set of imports, each of which is a valid import line in typescript
  @return the import block, on separate lines.