This is a simple app for understanding the behavior of `handle_on` and when `q.arg` dictionary is cleared.

testing_handlers_and_args.py

from h2o_wave import main, app, Q, ui, on, handle_on


@app('/')
async def serve(q: Q):
    if not q.client.initialized:  # first time a tab comes this is app
        q.page['a'] = ui.form_card(
            box='4 3 4 2',
            items=[
                ui.textbox(name='color_textbox', placeholder='Purple'),
                ui.button(name='color_submit', label='Submit', primary=True),

            ]
        )
        q.client.initialized = True
    else:  # if a tab is already active
        await handle_on(q)  # calls all "on" functions in order of q.args and stops after first match

    await q.page.save()


@on()
async def color_submit(q: Q):
    # In this app, this function is never called as we have a textbox with an on handled above the button
    print('Function: color_submit')
    print(f'Arguments: {str(q.args)}')

    q.page['b'] = ui.form_card(
        box='4 5 4 1',
        items=[
            ui.text(f'<center>I am the Button Handler: {q.args.color_textbox}</center>')
        ]
    )


@on()
async def color_textbox(q: Q):
    print('Function: color_textbox')
    print(f'Arguments: {str(q.args)}')

    q.page['c'] = ui.form_card(
        box='4 6 4 1',
        items=[
            ui.text(f'<center>I am the Textbox Handler: {q.args.color_textbox}</center>')
        ]
    )
    # We can call the other function from this function 
    # await color_submit(q)