function filterReteBiByBit( contentFilename ){
        let file = filesWithMetadata[contentFilename]
        if (!file) return
	// can be removed for URLs as those are not with metadata

        let contentType = file.contentType

	// mereology option
	let openingOptions = filesWithMetadata[contentFilename].openingOptions
	// can be used via e.g. showFile("https://fabien.benetou.fr/?action=source",{ mereology:"whole"})

	// filtering, only applying what's next to a certain content type and/or with filename filtering with .startsWith() .endsWith() .includes() or regex
        if ( contentType.includes("") && (contentFilename.endsWith("-rete.bitbybit") || contentFilename.endsWith("rete-runner.bitbybit") )) {
                console.log('it is a Rete BitByBit file', contentFilename)
		// assuming non minified code... but maybe works the same way
			// TODO try with minified code, would be preferred in order to do execution after

		const filenameIdPrefix = "retebitbybit_id_"
		if (contentFilename.endsWith("rete-runner.bitbybit") ) {
			fetch( contentFilename ).then( r => r.text() ).then( txt => {
				executeBitbybit(txt)
				// can keep track of generate meshes via
					// AFRAME.scenes[0].object3D.children.filter( o => o.name.includes("brepMesh") )
					// filtering with before the call and after (even though async)
			})
		} else {
			fetch( contentFilename ).then( r => r.json() ).then( txt => {
				let nodes = Object.entries( JSON.parse(txt.script).nodes )
				//console.log( nodes )

				const rootEl = document.createElement("a-entity")
				file.filteredEl = rootEl
				rootEl.execute = _ => console.warn( 'Not implemented for now, see executeBitbybit()')
				// TODO see executeBitbybit() , needs runner code too

				// function that can then be called on the created element later on
				// e.g. filesWithMetadata["https://companion.benetou.fr/saved/pdfxml/3209542.3209570.xml"].filteredEl.nextPage('ok')
				nodes.map( n => {
					let el = document.createElement("a-troika-text")
					let boxEl = document.createElement("a-box")
					boxEl.setAttribute("wireframe", "true" )
					boxEl.setAttribute("width", .3 )
					boxEl.setAttribute("height", .4 )
					boxEl.setAttribute("depth", .01 )
					boxEl.setAttribute("position", "0 -.18 0" )
					el.setAttribute("value", n[1].customName )
					el.setAttribute("font-size", ".05")
					el.setAttribute("target", "")
					let x = 1+n[1].position[0]/1000
					let y = 2-n[1].position[1]/1000
					let z = -1
					el.setAttribute("position", ""+x+" "+y+" "+z)
					rootEl.appendChild(el)
					el.appendChild(boxEl)
					el.id = filenameIdPrefix + n[1].id
				})
				nodes.map( p => {
					let n = p[1]
					let inputs = Object.entries( n.inputs ).map( o => o[1] )
					if (inputs.length) {
						// console.log( n.id, inputs )
						inputs.map( c => {
							let el = document.createElement("a-entity")
							el.setAttribute('live-selector-line',
								'start: #'+(filenameIdPrefix+n.id)
								+'; end: #'+(filenameIdPrefix+c.connections[0].node)
								+';' )
							el.classList.add('retebitbybit_export_link')
							rootEl.appendChild(el)
						})
					}
				})
				AFRAME.scenes[0].appendChild(rootEl)

				AFRAME.scenes[0].emit('retebitbybitloaded', contentFilename)
				// to use the event consider :
				//AFRAME.scenes[0].addEventListener("retebitbybitloaded", e => console.log(e))

			} ); 
		}
	}
        applyNextFilter( contentFilename )
	// can stop here or move on to the next filter that might or not be applied
}
sequentialFilters.push( filterReteBiByBit )
// adding this to the list of filters to go through, order matters
	// typically one would be generic filters first then more specific ones after

async function executeBitbybit(code){
    window.THREEJS = window.THREE; 
    await import("https://cdn.jsdelivr.net/gh/bitbybit-dev/bitbybit-assets@0.20.4/runner/bitbybit-runner-lite-threejs.js")
	    const aframeScene = document.querySelector('a-scene').object3D;
	    const runnerOptions = {
		canvasZoneClass: 'myCanvasZone',
		enableOCCT: true,
		enableJSCAD: false,
		enableManifold: false,
		loadFonts: ['Roboto'],
		externalThreeJSSettings: {
		    scene: aframeScene,
		    camera: AFRAME.systems.camera,
		}
	    };

	    const runner = window.bitbybitRunner.getRunnerInstance();
	    const { bitbybit, Bit, camera, scene, renderer } = await runner.run( runnerOptions);
	    window.bitbybit = bitbybit;
	    window.Bit = Bit;
	    window.runner = runner

	    runner.executeScript(code)
}