Getting error when trying to remove_widget() on ScreenManager Widget

[Jawann Jeffersom]

When I am attempting to remove a Screenmanager widget from a TabbedPanel i am getting the error mentioned in the title. I tracked it down to this function in TabbedPanel.py

def remove_widget(self, widget):
        content = self.content
        if content is None:
            return
        if widget in (content, self._tab_layout):
            super(TabbedPanel, self).remove_widget(widget)
        elif isinstance(widget, TabbedPanelHeader):
            if not (self.do_default_tab and widget is self._default_tab):
                self_tabs = self._tab_strip
                self_tabs.width -= widget.width
                self_tabs.remove_widget(widget)
                if widget.state == 'down' and self.do_default_tab:
                    self._default_tab.on_release()
                self._reposition_tabs()
            else:
                Logger.info('TabbedPanel: default tab! can\'t be removed.\n' +
                            'Change `default_tab` to a different tab.')
        else:
            self._childrens.pop(widget, None) <------Here 
            if widget in content.children:
                content.remove_widget(widget)

For some reason when i try to use remove_widget on a ScreenManager this throws an error. I did some debugging and found this is going into the function:  '((<WeakProxy to <__main__.HubTestsScreenManager object at 0x7fa07a623db8>>,), {})' as (self, widget) respectively. So does that mean when widget is used in the self._childrens.pop(widget, None) that no arg is being supplied. I don't think that is happening since it states 2 args are presented when it only accepts at most 1. 

I am calling i this way: self.remove_widget(self.usb_manager) where usb_manager is a ObjectProperty from my kv

class MainPanel(TabbedPanel):
    manager = ObjectProperty()
    usb_manager = ObjectProperty()
    hubtests_sm = ObjectProperty()


    def __init__(self, *args, **kwargs):

        super(MainPanel, self).__init__(*args, **kwargs)



    def switch_sm(self):
        self.manager = self.hubtests_sm
        self.remove_widget(self.usb_manager)
        self.add_widget(self.hubtests_sm)
main.kv
<MainPanel>:
    id: mp
    manager: usb_manager
    usb_manager: usb_manager


    size_hint: 1,1
    tab_width: 65
    do_default_tab: False
    tab_pos: 'top_right'


    TabbedPanelItem:
        id: usb_tab
        text: 'Usb'
        BoxLayout:
            orientation: 'vertical'
            UsbScreenManager:
                id: usb_manager
usb_screen_manager.kv

#:import label kivy.uix.label
#:import sla kivy.adapters.simplelistadapter
#:import hvd hub_validation_dict
#:import hvt hub_validation_test2
#:import cfg config

<UsbScreenManager>:
    id: usb_manager 
    h2h: h2h
    hvs: hvs
    v9_icon: v9_icon
    v9_test: v9_test
    c5_icon: c5_icon
    c5_test: c5_test

    H2HScreen:
        id:h2h
    HubValidationScreen:
        id:hvs
    V9ValidationIconScreen
        id: v9_icon
    V9ValidationTestScreen:
        id: v9_test
    C5ValidationIconScreen:
        id: c5_icon
    C5ValidationTestScreen:
        id: c5_test

<H2HScreen>:
    id: h2h
    name: 'h2h'
    BoxLayout:
        id:bl
        orientation: 'vertical'
        TestIcon:
            id: h2hicon
            source: 'h2h.png'


<HubValidationScreen>:
    id: hvs
    name: 'hvs'


    BoxLayout:
        id:bl
        orientation: 'vertical'

        TestIcon:
            id: hubvicon

            source: 'usb_button.png'
            on_press: app.root.switch_sm()<----Attempt to switch screenmanager


  File "/usr/lib/python2.7/dist-packages/kivy/lang.py", line 1465, in custom_callback
     exec(__kvlang__.co_value, idmap)
   File "usb_screen_manager.kv", line 53, in <module>
     on_press: app.root.switch_sm()
   File "sam1.py", line 211, in switch_sm
     self.remove_widget(self.usb_manager)
   File "/usr/lib/python2.7/dist-packages/kivy/uix/tabbedpanel.py", line 547, in remove_widget
     self._childrens.pop(widget, None)
 TypeError: pop() takes at most 1 argument (2 given)


Any help would be appreciated. 
Thanks