def serialized(request, queryset, format, mimetype=None):
    """
    Serialize queryset in specified format and return via HTTP
    Standard mimetype for format can be overridden with provided value
    """
    from django.http import HttpResponse
    from django.core import serializers
    content = serializers.serialize(format, queryset)
    if mimetype is None:
        if format == 'xml':
            mimetype = 'application/xml'
        elif format == 'json':
            # http://www.ietf.org/rfc/rfc4627.txt
            mimetype == 'application/json'
    return HttpResponse(content=content, mimetype=mimetype)