introduce isEmpty
introduce isEmpty

vogdb/cm,christopheschwyzer/CM,christopheschwyzer/CM,mariansollmann/CM,cargomedia/CM,fvovan/CM,njam/CM,njam/CM,cargomedia/CM,tomaszdurka/CM,fauvel/CM,mariansollmann/CM,zazabe/cm,alexispeter/CM,zazabe/cm,vogdb/cm,tomaszdurka/CM,christopheschwyzer/CM,fauvel/CM,alexispeter/CM,fauvel/CM,vogdb/cm,fvovan/CM,mariansollmann/CM,cargomedia/CM,tomaszdurka/CM,fauvel/CM,alexispeter/CM,mariansollmann/CM,njam/CM,tomaszdurka/CM,fvovan/CM,njam/CM,zazabe/cm,christopheschwyzer/CM,fauvel/CM,cargomedia/CM,vogdb/cm,alexispeter/CM,njam/CM,zazabe/cm,tomaszdurka/CM,fvovan/CM,vogdb/cm