docs: def create_host(url="local://local:6666/host"):
      '''
      This is the main function to create a new Host to which you can
      spawn actors. It will be set by default at local address if no
      parameter *url* is given, which would result in remote
      incomunication between hosts. This function shuould be called once
      for execution or after callig :meth:`~.shutdown` to the previous
      host.
  
      Nevertheless, it is possible to create locally more than one host
      and simulate a remote communication between them if they are of some
      remote type (`http` or `amqp`), but the first one created will
      be the main host, which is the one that will host the queries from
      the main function.
      Of course, every host must be initialized with a diferent URL(port).
      Although that, more than one host should not be requiered for any real
      project.
  
      :param str. url: URL where to start and bind the host.
      :return: :class:`~.Proxy` to the new host created.
      :raises: Exception if there is a host already created with that URL.
      '''
      if url in util.hosts.keys():
          raise HostError('Host already created. Only one host can' +
                          ' be ran with the same url.')
      else:
          if not util.hosts:
              util.main_host = Host(url)
              util.hosts[url] = util.main_host
          else:
              util.hosts[url] = Host(url)
          return util.hosts[url].proxy