@Override
	protected void print(PrintStream out, String indent) {
		out.print(indent + getSym() + " := " + prod);
		Collection<AssemblyConstructorSemantic> sems = grammar.getSemantics(prod);
		if (!sems.isEmpty()) {
			out.print(" (" + StringUtils.join(sems, ", ") + ")");
		}
		out.println();
		for (AssemblyParseTreeNode s : substs) {
			s.print(out, "  " + indent);
		}
	}
Check if the branch is full

@return true if every symbol on the RHS has a corresponding child
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/assembler/sleigh/tree/AssemblyParseBranch.java