[Closed] Pb accessing vertex position in edit mesh

well,what i’m trying to do is moving vertexes in an edit mesh modifier.
every mesh acces like

$foo.verts[i].pos = [10,0,0]

works fine as long as i work with
a collapsed editable mesh with no modifier present.
otherwise i get this :

– Runtime error: Cannot change mesh with modifiers present: Editable Mesh

so

how can i do things like moving vertex at a edit mesh modifier level ?