human
Solve the following python programming problem given the following code:
def _prepare_headers(self) : 
    headers = prepare_headers (self.request, self.shown_bound_columns) 
    header_groups = [] 
    class HeaderGroup (Struct) : 
        def render_css_class(self) : 
            return render_class (self.attrs ['class']) 
for (group_name, group_iterator) in groupby (headers, key = (lambda header : (header.group or id (header)))) : 
        header_group = list (group_iterator) 
        header_groups.append (HeaderGroup (display_name = group_name, sortable = False, colspan = len (header_group), attrs = Struct ({ 
            'class' : Struct (superheader = True), 
}))) 
        for x in header_group : 
            x.attrs ['class'] ['subheader'] = True 
            if x.is_sorting : 
                x.attrs ['class'] ['sorted_column'] = True 
header_group [0].attrs ['class'] ['first_column'] = True 
if header_groups : 
        header_groups [0].attrs ['class'] ['first_column'] = True 
for x in header_groups : 
        if (not isinstance (x.display_name, string_types)) : 
            x.display_name = '' 
if all ([(x.display_name == '') for x in headers]) : 
        header_groups = [] 
self.header_levels = ([header_groups, headers] if (len (header_groups) > 1) else [headers]) 
    return headers 

    
    

    Fix the buggy line: if all ([(x.display_name == '') for x in headers]) :
assistant
#Here is Python program to fix the buggy line: if all ([(x.

if all ([(x.display_name == '') for x in header_groups]) :