docs: public BaseTemplate pi(Map<?, ?> attrs) throws IOException {
          for (Map.Entry<?, ?> entry : attrs.entrySet()) {
              Object target = entry.getKey();
              Object instruction = entry.getValue();
              out.write("<?");
              if (instruction instanceof Map) {
                  out.write(target.toString());
                  writeAttributes((Map) instruction);
              } else {
                  out.write(target.toString());
                  out.write(" ");
                  out.write(instruction.toString());
              }
              out.write("?>");
              out.write(configuration.getNewLineString());
          }
          return this;
      }