def open_url(url, headers=None):
request = urllib2.Request(url)<EOL>if headers:<EOL><INDENT>for key, value in headers.items():<EOL><INDENT>request.add_header(key, value)<EOL><DEDENT><DEDENT>return URL_OPENER.open(request)<EOL>
Opens a URL. If headers are passed as argument, no check is performed and
the URL will be opened.

@param url: the URL to open
@type url: string

@param headers: the headers to use
@type headers: dictionary

@return: a file-like object as returned by urllib2.urlopen.