private CodeBlock createSub(AddressSetView set, Address entryPt) {

		CodeBlock sub = foundModelP.getBlockAt(entryPt);
		if (sub != null) {
// ?? May need to check if they have same AddressSet and entry points
			return sub;
		}

		Address[] starts = new Address[1];
		starts[0] = entryPt;
		sub = new CodeBlockImpl(this, starts, set);
		foundModelP.addObject(sub, set);
		return sub;
	}
Create a new Subroutine which has an address set and entry point.
@param  set the address set contained within the subroutine/block.
@param  entryPt the entry point address.
@return subroutine that was created
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/block/PartitionCodeSubModel.java