code: def metapolicy(request, permitted, domains=None):
      
      if domains is None:
          domains = []
      policy = policies.Policy(*domains)
      policy.metapolicy(permitted)
      return serve(request, policy)
docs: Serves a cross-domain policy which can allow other policies
      to exist on the same domain.
  
      Note that this view, if used, must be the master policy for the
      domain, and so must be served from the URL ``/crossdomain.xml`` on
      the domain: setting metapolicy information in other policy files
      is forbidden by the cross-domain policy specification.
  
      **Required arguments:**
  
      ``permitted``
          A string indicating the extent to which other policies are
          permitted. A set of constants is available in
          ``flashpolicies.policies``, defining acceptable values for
          this argument.
  
      **Optional arguments:**
  
      ``domains``
          A list of domains from which to allow access. Each value may
          be either a domain name (e.g., ``example.com``) or a wildcard
          (e.g., ``*.example.com``). Due to serious potential security
          issues, it is strongly recommended that you not use wildcard
          domain values.