a__fromXconsmarkXfromsXa__lengthnil0a__lengthconsXYsa__length1Ya__length1Xa__lengthXmarkfromXa__frommarkXmarklengthXa__lengthXmarklength1Xa__length1XmarkconsX1X2consmarkX1X2marksXsmarkXmarknilnilmark00a__fromXfromXa__lengthXlengthXa__length1Xlength1Xa__fromXmarkXa__lengthconsXYa__length1Ya__length1Xa__lengthXmarkfromXa__frommarkXmarkfromXmarkXmarklengthXa__lengthXmarklength1Xa__length1XmarkconsX1X2markX1marksXmarkXtruemarkfromXa__frommarkXa__fromXmarkXmarkfromXmarkXmarkconsX1X2markX1marksXmarkXtrue1231mark111from1111a__from111mark111cons211s111a__from1111a__length10nil00000a__length110length10length110a__fromXmarkXmarkconsX1X2markX1marksXmarkXa__fromXmarkXfalse1marksXmarkXmarkconsX1X2markX1true1mark111s111cons2111a__from1111mark111from1111a__length11nil00000a__length111length11length111marksXmarkX1mark111s1111a__from11cons2112mark1111from10a__length111nil01000a__length1111length111length1111marklength1Xa__length1Xfalse2marklengthXa__lengthXfalse1a__length1Xa__lengthXa__lengthconsXYa__length1Ytrue1a__length11111a__length1111cons2112a__from11mark1111from10s11a__length1111nil01001a__length11111length1111length11111a__length1Xa__lengthXa__length1Xa__lengthXfalse