human
I wrote the below code

    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(sub_metadata, line)
                line = line.lstrip('metadata    ')
        buf.append(line)
    return '\n'.join(buf)

What's a good function header?

=====
Here's a good function header?
assistant
#Here's a good function header.

def add_metadata_type(ir):