def concatenate(parts):
    part = parts[0]

    if is_old_style(part):
        # old-style parameters do not support any continuations
        return encodedword.mime_to_unicode(get_value(part))
    else:
        return u"".join(
            decode_new_style(p) for p in partition(parts))
Concatenates splitted parts of a parameter in a single parameter,
dataset/ETHPy150Open mailgun/flanker/flanker/mime/message/headers/parametrized.py/concatenate