method to return hierarchical siblings of this resource.

		Args:
			as_resources (bool): if True, opens each as appropriate resource type instead of return URI only

		Returns:
			(list): list of resources

def siblings(self, as_resources=False):

		'''
		method to return hierarchical siblings of this resource.

		Args:
			as_resources (bool): if True, opens each as appropriate resource type instead of return URI only

		Returns:
			(list): list of resources
		'''

		siblings = set()

		# loop through parents and get children
		for parent in self.parents(as_resources=True):
			for sibling in parent.children(as_resources=as_resources):
				siblings.add(sibling)

		# remove self
		if as_resources:
			siblings.remove(self)
		if not as_resources:
			siblings.remove(self.uri)

		return list(siblings)