human
Solve the following python programming problem given the following code:
def add_metadata_type(ir) : 
    '
    Rewrite metadata since llvm3.6 dropped the "metadata" type prefix.
    ' 
    buf = [] 
    for line in ir.splitlines () : 
        if re_metadata_def.match (line) : 
            if (None is re_metadata_correct_usage.search (line)) : 
                line = line.replace ('!{', 'metadata !{') 
                line = line.replace ('!"', 'metadata !"') 
                def sub_metadata(m) : 
                    return 'metadata {0}'.format (m.group (0)) 
line = re_metadata_ref.sub (buf, line) 
                line = line.lstrip ('metadata ') 
buf.append (line) 
return '
'.join (buf) 

    
    

    Fix the buggy line: line = re_metadata_ref.sub (buf, line)
assistant
#Here is Python program to fix the buggy line: line = re_metadata_ref.

line = re_metadata_ref.sub (def sub_metadata(, line)