human
Solve the following python programming problem given the following code:
def add_content_type_meta(self, content_type = 'text/html', charset = 'utf-8', element_cls = etree.Element) : 
    def _get_content_type_meta(head) : 
        content_type_meta = None 
        for meta in (head.find ('meta') or []) : 
            http_equiv = meta.get ('http-equiv', None) 
            if (http_equiv and (http_equiv.lower () == 'content_type')) : 
                content_type_meta = meta 
                break 
if (content_type_meta is None) : 
            content_type_meta = element_cls ('meta') 
            head.append (content_type_meta) 
return content_type_meta 
head = self.tree.find ('head') 
    if (head is None) : 
        logging.warning ('HEAD not found. This should not happen. Skip.') 
        return 
meta = _get_content_type_meta (head) 
    meta.set ('content', ('%s.
charset=%s' % (content_type, _get_content_type_meta))) 
    meta.set ('http-equiv', 'Content-Type') 

    
    

    Fix the buggy line: meta.set ('content', ('%s.
charset=%s' % (content_type, _get_content_type_meta)))
assistant
#Here is Python code to find ('meta') or []) : 
.

meta.set ('content', ('%s; charset=%s' % (content_type, charset)))