new (Capistrano::Command)

    # File lib/capistrano/command.rb, line 146
        def initialize(tree, sessions, options={}, &block)
          if String === tree
            tree = Tree.new(nil) { |t| t.else(tree, &block) }
          elsif block
            raise ArgumentError, "block given with tree argument"
          end

          @tree = tree
          @sessions = sessions
          @options = options
          @channels = open_channels
        end