Use multiple item flexform in flex using wec_content_element API

content.ts

tt_content.flex = COA
tt_content.flex {
    # render a field from the flexform
    10 = TEXT
    10 {
      data = t3datastructure : pi_flexform->titleField
    }
    
    # output each image in the flex.
    20 = FFSECTION
    20 {
        #declare which el from the flexform to render
        rootPath = t3datastructure : pi_flexform->images/el

        10 = COA
        10{
            # wrap images with content uid and then item index.
            # if the tt_content id is 123 and that the third displayed image : "c123_3"
            wrap =  <div id="c{field:uid}_{register:FFSECTION_COUNTER}" class="item" >|</div>
            wrap.insertData = 1

            10 = IMAGE
            10 {
                file.import.data = flexformSection : image/el/file
                file.import.wrap = uploads/skinFlex/timeline/
            }
        }
    }
}