[NTG-context] Lua-loop inside MetaPost

Hi all, I can't find a solution for the following example: \starttext \startMPpage draw origin for i=0 step 10 until 100 : ..{down}(i,0) endfor ; \stopMPpage \startluacode context.startMPpage() context("draw origin"..for i=0,100,10 do.."..{down}("..i..",0)"..end..";") context.stopMPpage() \stopluacode \stoptext Can someone help? Thanks in advance Andreas