```ruby
module WeiboOAuth2
  module Config
    
    def self.api_key=(val)
      @@api_key = val
    end
    
    def self.api_key
      @@api_key
    end
    
    def self.api_secret=(val)
      @@api_secret = val
    end
    
    def self.api_secret
      @@api_secret
    end
    
    def self.redirect_uri=(val)
      @@redirect_uri = val
    end
    
    def self.redirect_uri
      @@redirect_uri
    end

  end
end```

Fix initialization issue with access_token
user
```ruby
module WeiboOAuth2
  module Config
    
    def self.api_key=(val)
      @@api_key = val
    end
    
    def self.api_key
      @@api_key ||= nil
    end
    
    def self.api_secret=(val)
      @@api_secret = val
    end
    
    def self.api_secret
      @@api_secret ||= nil
    end
    
    def self.redirect_uri=(val)
      @@redirect_uri = val
    end
    
    def self.redirect_uri
      @@redirect_uri ||= nil
    end

  end
end
```
assistant