code: def _get_ports_list(app_name, port_specs):
      
      if app_name not in port_specs['docker_compose']:
          return []
      return ["{}:{}".format(port_spec['mapped_host_port'], port_spec['in_container_port'])
              for port_spec in port_specs['docker_compose'][app_name]]
docs: Returns a list of formatted port mappings for an app