public AssemblySentential<NT> sub(int fromIndex, int toIndex) {
		return new AssemblySentential<>(symbols.subList(fromIndex, toIndex));
	}
Trim leading and trailing whitespace, and make the sentential immutable
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/assembler/sleigh/grammars/AssemblySentential.java