class StaticContent:
    """This wsgi application provides static content on whatever request it
    receives."""
    def __init__(self, status, headers, content):
        """status is the HTTP status returned to the browser (ex: "200 OK")
        headers is a list of (header, value) pairs being delivered as HTTP
                headers
        content contains the data to be delivered to the client. It is either a
                string or some kind of iterable yielding strings.
        """
        assert isinstance(status, str)
        assert isinstance(headers, list)
        assert hasattr(content, "__iter__")
        self.status = status
        self.headers = headers
        length = -1
        if isinstance(content, basestring):
            self.content = [content]
            length = len(content)
        else:
            self.content = content
            if isinstance(self.content, list):
                length = sum(map(len, self.content))
        if length >= 0:
            if  not [v for h, v in headers if h.lower() == "content-length"]:
                headers.append(("Content-length", str(length)))
    def __call__(self, environ, start_response):
        """wsgi interface"""
        assert isinstance(environ, dict)
        start_response(self.status, self.headers)
        if environ["REQUEST_METHOD"].upper() == "HEAD":
            return []
        return self.content