def build_ReferencedLayout(screen):

	class Invalid_Property_Error(Exception): pass

	def has_ID(widget):
		return hasattr(widget, "id") and (widget.id != None)

	def has_Children(widget):
		return hasattr(widget, "children") and (len(widget.children) > 0)

	def validate_ID(parent, child, child_ID):
		if hasattr(parent, child_ID):
			raise Invalid_Property_Error(
				f"\n\t{parent} already has '{child_ID}' property."
				f"\n\t{child} cannot be added unless its ID is changed"
			)

	def add_Widget(parent, child, child_ID):
		child.id = child_ID
		if has_ID(parent):
			validate_ID(parent, child, child_ID)
			parent.__dict__[child_ID] = child
		else:
			validate_ID(layout, child, child_ID)
			layout.__dict__[child_ID] = child

	def add_Widget_IfNamed(parent, child):
		for ID, reference in namedWidgets:
			if child == reference:
				add_Widget(parent, child, ID)
				break

	def add_LayoutReferences(parent, namedWidgets):
		for child in reversed(parent.children):
			add_Widget_IfNamed(parent, child)
			if has_Children(child):
				add_LayoutReferences(child, namedWidgets)

	layout       = screen.ids.layout
	namedWidgets = screen.ids.items()
	add_LayoutReferences(layout, namedWidgets)
	return layout




###  StdLib  ###
import inspect

def get_MetaData(classReference, metaData_Type):

	class Invalid_MetaType_Error(Exception): pass

	class MetaData():
		def __init__(self, name, reference):
			self.name      = name
			self.reference = reference

	def get_TypeFilter():
		typeFilter = None
		if(metaData_Type == "functions"): return inspect.isfunction
		if(metaData_Type == "methods"  ): return inspect.ismethod

	def _get_MetaData(typeFilter):
		if(typeFilter):
			functions = inspect.getmembers(classReference, predicate=typeFilter)
			return [MetaData(x,y) for x,y in functions]
		else:
			raise Invalid_MetaType_Error(
				f"\n\t{metaData_Type} is not a valid meta-type"
			)

	typeFilter = get_TypeFilter()
	metaData   = _get_MetaData(typeFilter)
	return metaData