local p = {} local getArgs = require('Module:Arguments').getArgs  function p.Filter(frame) 	local args = getArgs(frame) 	local layers = args[1] or '' 	local filteredLayers = extract(layers,'W') 	if filteredLayers == '' then 		filteredLayers = 'M' -- currently there are only two acceptable base layer. 'M' will be set if 'W' is not specified 	end 	-- filteredLayers = 'O' -- once server functionality will be restored this line must be deleted 	-- Add additional & acceptable layer parameters 	filteredLayers = filteredLayers 		.. extract(layers,'S') -- hill shading from WM server 		.. extract(layers,'D') -- destination from Wikivoyage 		.. extract(layers,'G') -- GPX file from Wikivoyage 		.. extract(layers,'P') -- POI from Wikivoyage 		.. extract(layers,'E') -- add search box inside the map 	return filteredLayers end  function extract(layers, layer) 	if string.match(layers, layer) ~= nil then 		return string.match(layers, layer) 	else 		return '' 	end end  return p