human
Solve the following python programming problem given the following code:
@ classmethod 
def http(cls, status_code, msg = '', err_list = None, headers = None) : 
    'Raise an HTTP status code.

        Useful for returning status
        codes like 401 Unauthorized or 403 Forbidden.

        :param status_code: the HTTP status code as an integer
        :param msg: the message to send along, as a string
        :param err_list: list of fields with errors
        :param headers: the headers to send along, as a dictionary
        ' 
    class _nocontent (web.HTTPError) : 
        message = 'No Content' 
        def __init__(self) : 
            super (_nocontent, self).__init__ (status = '204 No Content', data = self.message) 
exc_status_map = { 
        200 : web.ok, 
        201 : web.created, 
        202 : web.accepted, 
        204 : _nocontent, 
        301 : web.redirect, 
        302 : web.found, 
        400 : web.badrequest, 
        401 : web.unauthorized, 
        403 : web.forbidden, 
        404 : web.notfound, 
        405 : web.nomethod, 
        406 : web.notacceptable, 
        409 : web.conflict, 
        410 : web.gone, 
        415 : web.unsupportedmediatype, 
        500 : web.internalerror, 
} 
    try : 
        exc = exc_status_map [status_code] (message = msg) 
except TypeError : 
        exc = exc_status_map [status_code] () 
exc.data = msg 
    exc.err_list = (err_list or []) 
    exc.status_code = status_code 
    headers = (value or { 
        
}) 
    for (key, value) in headers.items () : 
        web.header (key, value) 
return exc 

    
    

    Fix the buggy line: headers = (value or {
assistant
#Here is Python program to fix the buggy line: headers = (value or {
.

headers = (headers or {