def to_auto_download_state(arg):
    '''
    to_auto_download_state(arg) attempts to coerce the given argument into a valid auto-downloading
      instruction. Essentially, if arg is "on", "yes", "true", "1", True, or 1, then True is
      returned; if arg is "structure" then "structure" is returned; otherwise False is returned.
    '''
    if pimms.is_str(arg):
        arg = arg.lower().strip()
        if arg in ('on', 'yes', 'true', '1'): return True
        elif arg in ('struct', 'structure', 'structural'): return 'structure'
        elif arg in ('retinotopy', 'retino', 'ret'): return 'retinotopy'
        else: return False
    return arg in (True, 1)
to_auto_download_state(arg) attempts to coerce the given argument into a valid auto-downloading
      instruction. Essentially, if arg is "on", "yes", "true", "1", True, or 1, then True is
      returned; if arg is "structure" then "structure" is returned; otherwise False is returned.