diff --git a/src/mechanize/form.cr b/src/mechanize/form.cr
index 6143ab5..a993e3d 100644
--- a/src/mechanize/form.cr
+++ b/src/mechanize/form.cr
@@ -9,11 +9,11 @@ require "./form/select_list"
 require "./utils/element_matcher"
 
 # THis class represents the form tag of html.
-class MechanizeCr::Form
-  include MechanizeCr::ElementMatcher
+class Mechanize::Form
+  include Mechanize::ElementMatcher
 
   getter node : Node | Lexbor::Node
-  # returns an array of `MechanizeCr::FormContent::Field` in the form.
+  # returns an array of `Mechanize::FormContent::Field` in the form.
   getter fields : Array(FormContent::Field)
   # returns an array of input tags whose type is checkbox in the form.
   getter checkboxes : Array(FormContent::CheckBox)
diff --git a/src/mechanize/history.cr b/src/mechanize/history.cr
index 6cebd10..5448079 100644
--- a/src/mechanize/history.cr
+++ b/src/mechanize/history.cr
@@ -1,12 +1,13 @@
 require "./page"
 
-# This class represents the history of http response you sent.  
+# This class represents the history of http response you sent.
 # If you send a request, mechanize saves the history.
-class Mechanize::History
-  # max page size history can save. default is 100.  
-  # as same as `agent.max_history`.
-  property max_size : Int32
-  property array : Array(Mechanize::Page)
+class Mechanize
+  class History
+    # max page size history can save. default is 100.
+    # as same as `agent.max_history`.
+    property max_size : Int32
+    property array : Array(Mechanize::Page)
 
     delegate :size, :empty?, :last, to: array
 
@@ -15,17 +16,21 @@ class Mechanize::History
       @array = array
     end
 
-  # add page to history.
-  def push(page, uri = nil)
-    @array.push(page)
-    while size > @max_size
-      @array.shift
+    # add page to history.
+    def push(page, uri = nil)
+      @array.push(page)
+      while size > @max_size
+        @array.shift
+      end
+      self
     end
 
-  # take the last page out from history.
-  def pop
-    if size == 0
-      # TODO: raise error
+    # take the last page out from history.
+    def pop
+      if size == 0
+        # TODO: raise error
+      end
+      page = @array.pop
     end
   end
 end
diff --git a/src/mechanize/page.cr b/src/mechanize/page.cr
index d10e60a..ff952be 100644
--- a/src/mechanize/page.cr
+++ b/src/mechanize/page.cr
@@ -2,16 +2,15 @@ require "./file"
 require "./utils/element_matcher"
 require "./page/link"
 
-# This class represents the result of http response.  
-# If you send a request, it returns the instance of `Mechanize::Page`.  
+# This class represents the result of http response.
+# If you send a request, it returns the instance of `Mechanize::Page`.
 # You can get status code, title, and page body, and search html node using css selector from page instance.
-class Mechanize::Page < Mechanize::File
-  include Mechanize::ElementMatcher
+class Mechanize
+  class Page < Mechanize::File
+    include Mechanize::ElementMatcher
 
-  # look at lexbor document.(https://github.com/kostya/lexbor#readme)
-  delegate :css, to: parser
-
-  property mech : Mechanize
+    # look at lexbor document.(https://github.com/kostya/lexbor#readme)
+    delegate :css, to: parser
 
     property mech : Mechanize
 
@@ -20,41 +19,48 @@ class Mechanize::Page < Mechanize::File
       super(uri, response, body, code)
     end
 
-  # return page title.
-  # ```
-  # page.title # => String
-  # ```
-  def title : String
-    title_node = css("title")
-    if title_node.empty?
-      ""
-    else
-      title_node.first.inner_text
+    # parser to parse response body.
+    # TODO: now it's Lexbor::Parser. I want to also support other parsers like JSON.
+    def parser : Lexbor::Parser
+      @parser ||= Lexbor::Parser.new(@body)
     end
 
-  # return all forms(`Mechanize::Form`) in the page.
-  # ```
-  # page.forms # => Array(Mechanize::Form)
-  # ```
-  def forms : Array(Mechanize::Form)
-    forms = css("form").map do |html_form|
-      form = Form.new(html_form, self)
-      form.action ||= @uri.to_s
-      form
-    end.to_a
-  end
-
-  # return all links(`Mechanize::PageContent::Link`) in the page.
-  # ```
-  # page.links # => Array(Mechanize::PageContent::Link)
-  # ```
-  def links : Array(Mechanize::PageContent::Link)
-    links = %w{a area}.map do |tag|
-      css(tag).map do |node|
-        PageContent::Link.new(node, @mech, self)
+    # return page title.
+    # ```
+    # page.title # => String
+    # ```
+    def title : String
+      title_node = css("title")
+      if title_node.empty?
+        ""
+      else
+        title_node.first.inner_text
       end
-    end.flatten
-  end
+    end
+
+    # return all forms(`Mechanize::Form`) in the page.
+    # ```
+    # page.forms # => Array(Mechanize::Form)
+    # ```
+    def forms : Array(Mechanize::Form)
+      forms = css("form").map do |html_form|
+        form = Form.new(html_form, self)
+        form.action ||= @uri.to_s
+        form
+      end.to_a
+    end
+
+    # return all links(`Mechanize::PageContent::Link`) in the page.
+    # ```
+    # page.links # => Array(Mechanize::PageContent::Link)
+    # ```
+    def links : Array(Mechanize::PageContent::Link)
+      links = %w{a area}.map do |tag|
+        css(tag).map do |node|
+          PageContent::Link.new(node, @mech, self)
+        end
+      end.flatten
+    end
 
     elements_with "form"
   end
diff --git a/src/mechanize/utils/element_matcher.cr b/src/mechanize/utils/element_matcher.cr
index 5ca3f09..f36d262 100644
--- a/src/mechanize/utils/element_matcher.cr
+++ b/src/mechanize/utils/element_matcher.cr
@@ -1,71 +1,71 @@
 class Mechanize
   module ElementMatcher
     macro elements_with(singular, plural = "")
-    {% plural = "#{singular.id}s" if plural.empty? %}
-    # search {{ plural.id }} which match condition.
-    # 
-    # Examples
-    # ```
-    # # if you specify String like "foo", it searches form which name is "foo".
-    {% if ["form", "button"].includes?("#{singular.id}") %}
-      # # like <{{ singular.id }} name="foo"></{{ singular.id }}>
-    {% elsif "#{singular.id}" == "field" %}
-    # # like <input name="foo"></input>
-    {% elsif "#{singular.id}" == "radiobutton" %}
-    # # like <input type="radio" name="foo"></input>
-    {% else %}
-    # # like <input type="{{ singular.id }}" name="foo"></input>
-    {% end %}
-    # page.{{ plural.id }}_with("foo")
-    # # you can also specify tag's attribute and its' value by NamedTuple or Hash(String, String).
-    {% if ["form", "button"].includes?("#{singular.id}") %}
-    # # ex) <{{ singular.id }} class="foo"></{{ singular.id }}>
-    {% elsif "#{singular.id}" == "field" %}
-    # # ex) <input class="foo"></input>
-    {% elsif "#{singular.id}" == "radiobutton" %}
-    # # ex) <input type="radio" class="foo"></input>
-    {% else %}
-    # # ex) <input type="{{ singular.id }}" class="foo"></input>
-    {% end %}
-    # page.{{ plural.id }}_with("class" => "foo")
-    # page.{{ plural.id }}_with(class: "foo")
-    # ```
-    def {{plural.id}}_with(criteria : String | NamedTuple | Hash(String,String))
-      {{plural.id}}_with(criteria){}
-    end
+      {% plural = "#{singular.id}s" if plural.empty? %}
+      # search {{ plural.id }} which match condition.
+      # 
+      # Examples
+      # ```
+      # # if you specify String like "foo", it searches form which name is "foo".
+      {% if ["form", "button"].includes?("#{singular.id}") %}
+        # # like <{{ singular.id }} name="foo"></{{ singular.id }}>
+      {% elsif "#{singular.id}" == "field" %}
+      # # like <input name="foo"></input>
+      {% elsif "#{singular.id}" == "radiobutton" %}
+      # # like <input type="radio" name="foo"></input>
+      {% else %}
+      # # like <input type="{{ singular.id }}" name="foo"></input>
+      {% end %}
+      # page.{{ plural.id }}_with("foo")
+      # # you can also specify tag's attribute and its' value by NamedTuple or Hash(String, String).
+      {% if ["form", "button"].includes?("#{singular.id}") %}
+      # # ex) <{{ singular.id }} class="foo"></{{ singular.id }}>
+      {% elsif "#{singular.id}" == "field" %}
+      # # ex) <input class="foo"></input>
+      {% elsif "#{singular.id}" == "radiobutton" %}
+      # # ex) <input type="radio" class="foo"></input>
+      {% else %}
+      # # ex) <input type="{{ singular.id }}" class="foo"></input>
+      {% end %}
+      # page.{{ plural.id }}_with("class" => "foo")
+      # page.{{ plural.id }}_with(class: "foo")
+      # ```
+      def {{plural.id}}_with(criteria : String | NamedTuple | Hash(String,String))
+        {{plural.id}}_with(criteria){}
+      end
 
-    def {{plural.id}}_with(criteria, &block)
-      if criteria.is_a?(NamedTuple)
-        criteria = criteria.to_h
-      end
-      if criteria.is_a?(String)
-        criteria = {"name" => criteria}
-      else
-        criteria = criteria.each_with_object(Hash(String,String).new) do |(k, v), h|
-          k = k.to_s
-          h[k] = v
+      def {{plural.id}}_with(criteria, &block)
+        if criteria.is_a?(NamedTuple)
+          criteria = criteria.to_h
         end
-      end
-      f = {{plural.id}}.select do |elm|
-        criteria.all? do |k,v|
-          if k == "text"
-            v == elm.node.inner_text
-          else
-            v == elm.node.fetch(k,"")
+        if criteria.is_a?(String)
+          criteria = {"name" => criteria}
+        else
+          criteria = criteria.each_with_object(Hash(String,String).new) do |(k, v), h|
+            k = k.to_s
+            h[k] = v
           end
         end
+        f = {{plural.id}}.select do |elm|
+          criteria.all? do |k,v|
+            if k == "text"
+              v == elm.node.inner_text
+            else
+              v == elm.node.fetch(k,"")
+            end
+          end
+        end
+        yield f
+        f
       end
-      yield f
-      f
-    end
 
-    # returns first element of `#{{ plural.id }}_with`
-    def {{singular.id}}_with(criteria)
-      f = {{plural.id}}_with(criteria)
-      # TODO: Write correct error message.
-      raise Mechanize::ElementNotFoundError.new(:{{singular.id}}, "") if f.empty?
-      f.first
+      # returns first element of `#{{ plural.id }}_with`
+      def {{singular.id}}_with(criteria)
+        f = {{plural.id}}_with(criteria)
+        # TODO: Write correct error message.
+        raise Mechanize::ElementNotFoundError.new(:{{singular.id}}, "") if f.empty?
+        f.first
+      end
     end
   end
-  end
 end