How to use the net.isIP function in net

const getIps = async address => {
  if(net.isIP(address)) {
    return Promise.resolve([ address ]);
  }
  return new Promise((resolve, reject) => {
    dns.resolve4(address, (err, ips) => {
      if(err) {
        return reject(err);
      }
      if(ips.sort) {
        ips = ips.sort();
      }
      return resolve(ips);
    });
  });
};

function getForwardedFor(headers) {
  var val = headers[config.CLIENT_IP_HEAD];
  if (!val || typeof val !== 'string') {
    return '';
  }
  var index = val.indexOf(',');
  if (index !== -1) {
    val = val.substring(0, index);
  }
  val = removeIPV6Prefix(val.trim());
  return net.isIP(val) && !isLocalAddress(val) ? val : '';
}
exports.getForwardedFor = getForwardedFor;

var isIP = function(address) {
    if (!net) net = require('net');
    return net.isIP(address);
};