@Override
	public int hashCode() {
		int result = 0;
		result += prod.getIndex();
		result *= 31;
		result += pos;
		return result;
	}
"Fill" one step out to close a state containing this item

<p>
To compute the full closure, you must continue stepping out until no new items are generated

@param grammar the grammar containing the production
@return a subset of items in the closure of a state containing this item
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/assembler/sleigh/parse/AssemblyParseStateItem.java