def sibling_index
			node_maps = self.survey.node_maps

			if node_map = node_maps.select { |i| i.node == self }.first
				parent = node_map.parent

				children = node_maps.select { |i| i.parent && i.parent.node === parent.node }

				children.each_with_index { |nm, i|
					if nm == node_map
						return i
					end
				}
			end
		end
def sibling_index
			node_maps = self.survey.node_maps

			if node_map = node_maps.select { |i| i.node == self }.first
				parent = node_map.parent

				children = node_maps.select { |i| i.parent && i.parent.node === parent.node }

				children.each_with_index { |nm, i|
					if nm == node_map
						return i
					end
				}
			end
		end
Gets index in sibling relationship