How to use the core-util-is.isNumber function in core-util-is

Readable.prototype.read = function(n) {
  debug('read', n);
  var state = this._readableState;
  var nOrig = n;

  if (!util.isNumber(n) || n > 0)
    state.emittedReadable = false;

  // if we're doing read(0) to trigger a readable event, but we
  // already have a bunch of data in the buffer, then just trigger
  // the 'readable' event and move on.
  if (n === 0 &&
      state.needReadable &&
      (state.length >= state.highWaterMark || state.ended)) {
    debug('read: emitReadable', state.length, state.ended);
    if (state.length === 0 && state.ended)
      endReadable(this);
    else
      emitReadable(this);
    return null;
  }

Readable.prototype.read = function(n) {
  debug('read', n);
  var state = this._readableState;
  var nOrig = n;

  if (!util.isNumber(n) || n > 0)
    state.emittedReadable = false;

  // if we're doing read(0) to trigger a readable event, but we
  // already have a bunch of data in the buffer, then just trigger
  // the 'readable' event and move on.
  if (n === 0 &&
      state.needReadable &&
      (state.length >= state.highWaterMark || state.ended)) {
    debug('read: emitReadable', state.length, state.ended);
    if (state.length === 0 && state.ended)
      endReadable(this);
    else
      emitReadable(this);
    return null;
  }

const get_indent = space => isString(space)
  // If the space parameter is a string, it will be used as the indent string.
  ? space
  : isNumber(space)
    ? repeat(SPACE, space)
    : EMPTY

Readable.prototype.read = function(n) {
  debug('read', n);
  var state = this._readableState;
  var nOrig = n;

  if (!util.isNumber(n) || n > 0)
    state.emittedReadable = false;

  // if we're doing read(0) to trigger a readable event, but we
  // already have a bunch of data in the buffer, then just trigger
  // the 'readable' event and move on.
  if (n === 0 &&
      state.needReadable &&
      (state.length >= state.highWaterMark || state.ended)) {
    debug('read: emitReadable', state.length, state.ended);
    if (state.length === 0 && state.ended)
      endReadable(this);
    else
      emitReadable(this);
    return null;
  }

Readable.prototype.read = function(n) {
  debug('read', n);
  var state = this._readableState;
  var nOrig = n;

  if (!util.isNumber(n) || n > 0)
    state.emittedReadable = false;

  // if we're doing read(0) to trigger a readable event, but we
  // already have a bunch of data in the buffer, then just trigger
  // the 'readable' event and move on.
  if (n === 0 &&
      state.needReadable &&
      (state.length >= state.highWaterMark || state.ended)) {
    debug('read: emitReadable', state.length, state.ended);
    if (state.length === 0 && state.ended)
      endReadable(this);
    else
      emitReadable(this);
    return null;
  }

Readable.prototype.read = function(n) {
  debug('read', n);
  var state = this._readableState;
  var nOrig = n;

  if (!util.isNumber(n) || n > 0)
    state.emittedReadable = false;

  // if we're doing read(0) to trigger a readable event, but we
  // already have a bunch of data in the buffer, then just trigger
  // the 'readable' event and move on.
  if (n === 0 &&
      state.needReadable &&
      (state.length >= state.highWaterMark || state.ended)) {
    debug('read: emitReadable', state.length, state.ended);
    if (state.length === 0 && state.ended)
      endReadable(this);
    else
      emitReadable(this);
    return null;
  }

Readable.prototype.read = function(n) {
  debug('read', n);
  var state = this._readableState;
  var nOrig = n;

  if (!util.isNumber(n) || n > 0)
    state.emittedReadable = false;

  // if we're doing read(0) to trigger a readable event, but we
  // already have a bunch of data in the buffer, then just trigger
  // the 'readable' event and move on.
  if (n === 0 &&
      state.needReadable &&
      (state.length >= state.highWaterMark || state.ended)) {
    debug('read: emitReadable', state.length, state.ended);
    if (state.length === 0 && state.ended)
      endReadable(this);
    else
      emitReadable(this);
    return null;
  }

function determineDelay(delayInput) {
	var result = 0,
		range, upper, lower;
	if (util.isNumber(delayInput)) {
		result = delayInput;
	} else if (util.isString(delayInput)) {
		range = /([0-9]+)..([0-9]+)/.exec(delayInput);
		upper = +range[2];
		lower = +range[1];
		result = Math.floor(Math.random() * (upper - lower + 1) + lower);
	}

	return result;
}

listen (port) {
    const realPort = port
      || this._port
      || this._configLoader && this._configLoader.prop('port')

    if (!isNumber(realPort)) {
      throw error('INVALID_PORT', realPort)
    }

    this._port = realPort

    return new Promise(resolve => {
      this.server.listen(realPort, resolve)
    })
  }
}

exports.int = function (obj) {
  return utils.isNumber(obj)
    && obj % 1 === 0;
};