Capistrano

    # File lib/capistrano/extensions.rb, line 20
20:   def self.plugin(name, mod)
21:     name = name.to_sym
22:     return false if EXTENSIONS.has_key?(name)
23: 
24:     methods = Capistrano::Configuration.public_instance_methods +
25:       Capistrano::Configuration.protected_instance_methods +
26:       Capistrano::Configuration.private_instance_methods
27: 
28:     if methods.any? { |m| m.to_sym == name }
29:       raise Capistrano::Error, "registering a plugin named `#{name}' would shadow a method on Capistrano::Configuration with the same name"
30:     end
31: 
32:     Capistrano::Configuration.class_eval       def #{name}        @__#{name}_proxy ||= Capistrano::ExtensionProxy.new(self, Capistrano::EXTENSIONS[#{name.inspect}])      end, __FILE__, __LINE__+1
33: 
34:     EXTENSIONS[name] = mod
35:     return true
36:   end

    # File lib/capistrano/extensions.rb, line 43
43:   def self.remove_plugin(name)
44:     name = name.to_sym
45:     if EXTENSIONS.delete(name)
46:       Capistrano::Configuration.send(:remove_method, name)
47:       return true
48:     end
49: 
50:     return false
51:   end

     # File lib/capistrano/shell.rb, line 257
257:     def sessions
258:       configuration.sessions.values
259:     end