mechanize：Mechanize#visited?

>> require 'mechanize'
=> true
>> agent = Mechanize.new
=> #<Mechanize:0xb74f835c ...
>> agent.visited?("http://www.foo.org/")
=> false
>> agent.visited?("http://www.google.com/")
=> false
>> agent.get("http://www.google.com/")
=> #<Mechanize::Page
 {url #<URI::HTTP:0xb74e6d50 URL:http://www.google.co.jp/>}
  ...
>> agent.visited?("http://www.google.com/")
=> true
>> agent.max_history = 0
=> 0
>> agent.visited?("http://www.google.com/")
=> true
>> agent.get("http://www.yahoo.co.jp/")
=> #<Mechanize::Page
 {url #<URI::HTTP:0xb74a691c URL:http://www.yahoo.co.jp/>}
  ...
>> agent.visited?("http://www.yahoo.co.jp/")
=> false
>> agent.max_history = 1
=> 1
>> agent.get("http://www.yahoo.co.jp/")
=> #<Mechanize::Page
 {url #<URI::HTTP:0xb742e0ac URL:http://www.yahoo.co.jp/>}
  ...
>> agent.visited?("http://www.yahoo.co.jp/")
=> true