f contents.
  return false for key, val of a when !(key of b) or !_.isEqual(val, b[key])
  true


# Is a given array or object empty?
_.isEmpty = (obj) ->
  return obj.length is 0 if _.isArray(obj) or _.isString(obj)
  return false for own key of obj
  true


# Is a given value a DOM element?
_.isElement = (obj) -> obj and obj.nodeType is 1


# Is a given value an array?
_.isArray = nativeIsArray or (obj) -> !!(obj and obj.concat and obj.unshift and not obj.callee)


# Is a given variable an arguments objec