function isStandardSyntaxValue(value) {
  let normalizedValue = value;

  // Ignore operators before variables (example -$variable)
  if (/^[-+*/]/.test(value.charAt(0))) {
    normalizedValue = normalizedValue.slice(1);
  }

  // SCSS variable (example $variable)
  if (normalizedValue.startsWith("$")) {
    return false;
  }

  // SCSS namespace (example namespace.$variable)
  if (/^.+\.\$/.test(value)) {
    return false;
  }

  // SCSS namespace (example namespace.function-name())
  if (/^.+\.[-\w]+\(/.test(value)) {
    return false;
  }

  // Less variable
  if (normalizedValue.startsWith("@")) {
    return false;
  }

  // SCSS or Less interpolation
  if (hasInterpolation(normalizedValue)) {
    return false;
  }

  // WebExtension replacement keyword used by Chrome/Firefox
  // more information: https://developer.chrome.com/extensions/i18n
  // and https://github.com/stylelint/stylelint/issues/4707
  if (/__MSG_\S+__/.test(value)) {
    return false;
  }

  return true;
}
Check whether a value is standard

@param {string} value
@returns {boolean}