def find_separator(str):
    """
    Find a common separators used in Youtube titles to separate artist and
    track name.
    """
    separators = [' -- ', ' - ', ' – ', ' — ', '///', '►']
    if len(str) == 0:
        return None

    for sep in separators:
        index = str.find(sep)
        if index > -1:
            return {
                "index": index,
                "length": len(sep)
            }

    return None