import bpy
import bmesh


def mission1(scn):

    obj = scn.objects.active
    if bpy.context.mode == 'EDIT_MESH':
        bm = bmesh.from_edit_mesh(obj.data)
    else:
        bm = bmesh.new()
        bm.from_object(obj, scn)

    v2 = bm.verts.new( [0,7,0] )

    bm.verts.ensure_lookup_table()

    v1 = bm.verts[3]

    e1 = bm.edges.new( [v1, v2] )

    f1 = bm.faces.new( [v1, v2, bm.verts[7]])

    if bpy.context.mode == 'EDIT_MESH':
        bmesh.update_edit_mesh(obj.data)
    else:
        bm.to_mesh(obj.data)

    obj.data.update()

mission1(bpy.context.scene)