def get_markdown_files(self, dir_):
md_files = OrderedSet()<EOL>for root, _, files in os.walk(dir_):<EOL><INDENT>for name in files:<EOL><INDENT>split = os.path.splitext(name)<EOL>if len(split) == <NUM_LIT:1>:<EOL><INDENT>continue<EOL><DEDENT>if split[<NUM_LIT:1>] in ('<STR_LIT>', '<STR_LIT>', '<STR_LIT>'):<EOL><INDENT>md_files.add(os.path.join(root, name))<EOL><DEDENT><DEDENT><DEDENT>return md_files<EOL>
Get all the markdown files in a folder, recursively

Args:
    dir_: str, a toplevel folder to walk.