Trying to figure out why app reloads

app_reload.py

from bokeh.properties import Instance, Bool, String
from bokeh.models.widgets.buttons import Button, Toggle
from bokeh.models.widgets.markups import Paragraph
from bokeh.models.widgets.layouts import VBox, HBox, VBoxForm
from bokeh.models.widgets.inputs import Select
from bokeh.server.app import bokeh_app
from bokeh.server.utils.plugins import object_page
from bokeh.plotting import curdoc


class MenuChange(VBox):
    extra_generated_classes = [["MenuChange", "MenuChange", "VBox"]]
    jsmodel = "VBox"

    # layout boxes
    mainrow = Instance(HBox)
    input_box = Instance(VBoxForm)
    paragraph = Instance(Paragraph)

    # inputs
    menu_submit = Instance(Button)
    menu_toggle = Instance(Toggle)
    type_select = Instance(Select)
    toggle_active = Bool(default=False)
    types = String(default='1')

    def __init__(self, *args, **kwargs):
        super(MenuChange, self).__init__(*args, **kwargs)

    @classmethod
    def create(cls):
        obj = cls()
        obj.input_box = VBoxForm()
        obj.mainrow = HBox()
        obj.paragraph = Paragraph(text='Select something.')
        obj.set_inputs()
        obj.set_children()

        return obj

    def set_inputs(self):
        self.menu_toggle = Toggle(label='Select plot criteria', type='primary')
        self.type_select = Select(value='1', options=['1', '2', '3'])
        self.menu_submit = Button(label='Submit', type='warning')

    def set_children(self):
        if self.toggle_active:
            self.menu_toggle.label = 'Cancel'
            self.mainrow.children = [self.menu_submit, self.menu_toggle, self.type_select]
        else:
            self.menu_toggle.label = 'Select plot criteria'
            self.mainrow.children = [self.menu_toggle]
        self.input_box.children = [self.mainrow]
        self.children = [self.input_box, self.paragraph]
        curdoc().add(self)

    def toggle_menu(self, obj, attr, old, new):
        self.toggle_active = new
        if new:
            self.menu_toggle.label = 'Cancel'
            self.mainrow.children = [self.menu_submit, self.menu_toggle, self.type_select]
        else:
            self.menu_toggle.label = 'Select plot criteria'
            self.mainrow.children = [self.menu_toggle]

    def submit_menu(self, obj, attr, old, new):
        self.paragraph.text = self.types
        self.toggle_menu(None, None, None, False)

    def set_selection(self, obj, attr, old, new):
        if obj == self.type_select:
            self.types = new

    def setup_events(self):
        super(MenuChange, self).setup_events()
        if self.menu_submit:
            self.menu_submit.on_change('clicks', self, 'submit_menu')
        if self.menu_toggle:
            self.menu_toggle.on_change('active', self, 'toggle_menu')
        if self.type_select:
            self.type_select.on_change('value', self, 'set_selection')

@bokeh_app.route("/bokeh/menu_change/")
@object_page("menu_change")
def make_menu():
    app = MenuChange.create()
    return app