help needed on angular schematic

[lim-enhui]

Hi I am not very clear with the statement below... I don't get a picture to know how chain, branchAndMerge work also mergeWith.... Can you show me a drawing of how the pattern works??

      const rule = chain([
        branchAndMerge(chain([
          mergeWith(templateSource),
          
          addDeclarationToNgModule(options, options.export),
          injectServiceIntoAppComponent(options)
        ]))
      ]);