public long countRefsOnLine(int line) {
		return usage.readersAndWriters()
				.filter(u -> u.location().line() == line)
				.count();
	}
Models a variable.

@param name
		Name of label.
@param usage
		Usages of the loabel in the AST.
recaf-ui/src/main/java/software/coley/recaf/ui/pane/editing/assembler/LabelData.java