.getVariable("block")
.invokeInterface(com.facebook.presto.spi.block.Block.class, "getPositionCount", int.class)
.putVariable(rowsVariable);
IfStatementBuilder builder = ifStatementBuilder(context);
builder.comment("if(!block.isNull(position))")
.condition(new Block(context)
.getVariable("block")
.getVariable(positionVariable)
.invokeInterface(com.facebook.presto.spi.block.Block.class, "isNull", boolean.class, int.class))
.ifTrue(NOP)