code: function isValidAtomicRule(rule) {
    const decls = rule.nodes.filter(node => node.type === "decl");
    if (decls.length < 0) {
      return { isValid: true };
    }
  
    for (let i = 1; i < decls.length; i++) {
      const current = decls[i].prop;
      const prev = decls[i - 1].prop;
      if (current < prev) {
        const loc = {
          start: {
            line: decls[i - 1].source.start.line,
            column: decls[i - 1].source.start.column - 1
          },
          end: {
            line: decls[i].source.end.line,
            column: decls[i].source.end.column - 1
          }
        };
  
        return { isValid: false, loc };
      }
    }
  
    return { isValid: true };
  }
docs: An atomic rule is a rule without nested rules.