pry--pry/lib/pry/commands/switch_to.rb

class Pry
  Pry::Commands.create_command "switch-to" do
    group 'Navigating Pry'
    description "Start a new sub-session on a binding in the current stack " \
      "(numbered by nesting)."

    def process(selection)
      selection = selection.to_i

      if selection < 0 || selection > _pry_.binding_stack.size - 1
        raise CommandError, "Invalid binding index #{selection} - use `nesting` command to view valid indices."
      else
        Pry.start(_pry_.binding_stack[selection])
      end
    end
  end
end