README.md in option_initializer-1.3.0 vs README.md in option_initializer-1.5.0

@@ -13,16 +13,19 @@
 ```ruby
 require 'option_initializer'
 
 class Person
   include OptionInitializer
-  option_initializer :id, :name, :greetings => :block, :birthday => 1..3
-  option_validator do |k, v|
-    case k
-    when :name
-      raise ArgumentError, "invalid name" if v.empty?
-    end
+
+  option_initializer :id,
+                     :name => String,
+                     :greetings => :&,
+                     :birthday => 1..3,
+                     :sex => Set[:male, :female]
+
+  option_validator :name do |v|
+    raise ArgumentError, "invalid name" if v.empty?
   end
 
   def initialize opts
     validate_options opts
     @options = opts
@@ -37,17 +40,19 @@
 john = Person.
          name('John Doe').
          birthday(1990, 1, 1).
          greetings { |name| "Hi, I'm #{name}!" }.
          id(1000).
+         sex(:male).
          new
 
 # becomes equivalent to
 john = Person.new(
          :id => 1000,
          :name => 'John Doe',
          :birthday => [1990, 1, 1],
+         :sex => :male,
          :greetings => proc { |name| "Hi, I'm #{name}!" }
        )
 
 # Method call shortcut
 class Person
@@ -60,5 +65,53 @@
   greetings { |name| "Hi, I'm #{name}!" }.
   id(1000).
   say_hello
 ```
 
+## Option definitions and validators
+
+```ruby
+class MyClass
+  include OptionInitializer
+
+  option_initializer :a,                              # Single object of any type
+                     :b => 2,                         # Two objects of any type
+                     :c => 1..3,                      # 1, 2, or 3 objects of any type
+                     :d => :*,                        # Any number of objects of any type
+                     :e => :&,                        # Block
+                     :f => Fixnum,                    # Single Fixnum object
+                     :g => [Fixnum, String, Symbol],  # Fixnum, String, and Symbol
+                     :h => Set[true, false],          # Value must be either true or false
+                     :i => [Fixnum, Set[true, false]] # Fixnum and boolean
+
+  # Validator for :f
+  option_validator :f do |v|
+    raise ArgumentError if v < 0
+  end
+
+  # Generic validator
+  option_validator do |k, v|
+    case k
+    when :a
+      # ...
+    when :b
+      # ...
+    end
+  end
+
+  def initialize arg1, arg2, options
+    validate_options options
+    @options = options
+  end
+end
+
+object = MyClass.a(o).
+                 b(o1, o2).
+                 c(o1, o2, o3).
+                 d(o1, o2).
+                 e { |o| o ** o }.
+                 f(f).
+                 g(f, str, sym).
+                 h(true).
+                 i(100, false).
+                 new(a1, a2)
+```