While waiting the official answer, I found the work around thanks to these posts:
In 3. Custom HTML python code
def my_method(self, name):
print (name)
self.parent.raise_event('x-update-label', new_text = name)
in 3. Custom HTML - HTML code
// change $('.content') to this
function myFunc() {
anvil.call(this, 'my_method', 'world')
}
in 2 Blank Panel
def __init__(self, **properties):
# Set Form properties and Data Bindings.
self.init_components(**properties)
self.set_event_handler('x-update-label', self.update_label)
def update_label(self, new_text, **event_args):
print (new_text+ "++++++++++++==")