code: function isBoolean(value) {
      return value === true || value === false ||
        value && typeof value == 'object' && toString.call(value) == boolClass || false;
    }
docs: Checks if `value` is a boolean value.
  
  @static
  @memberOf _
  @category Objects
  @param {*} value The value to check.
  @returns {boolean} Returns `true` if the `value` is a boolean value, else `false`.
  @example
  
  _.isBoolean(null);
  // => false