code: function isNumber(value) {
      return typeof value == 'number' ||
        value && typeof value == 'object' && toString.call(value) == numberClass || false;
    }
docs: Checks if `value` is a number.
  
  Note: `NaN` is considered a number. See http://es5.github.io/#x8.5.
  
  @static
  @memberOf _
  @category Objects
  @param {*} value The value to check.
  @returns {boolean} Returns `true` if the `value` is a number, else `false`.
  @example
  
  _.isNumber(8.4 * 5);
  // => true