code: public FaunusPipeline map() {
          this.state.assertNotLocked();
          this.state.assertNoProperty();
  
          this.compiler.addMap(PropertyMapMap.Map.class,
                  LongWritable.class,
                  Text.class,
                  PropertyMapMap.createConfiguration(this.state.getElementType()));
          makeMapReduceString(PropertyMap.class);
          this.state.lock();
          return this;
      }
docs: Emit a string representation of the property map.
  
  @return the extended FaunusPipeline