protected boolean allUnknown(int startindex,int length) {
		for(int i=0;i<length;++i)
			if (instList[startindex + i].isMatched)
				return false;
		return true;
	}
If the indicated n-gram, within this block, consists of unmatched instructions
@param startindex is the index of the first Instruction in the n-gram
@param length is the number of instructions in the n-gram
@return true if all Instructions in the n-gram are not matched, false otherwise.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/correlate/Block.java