def create_mount_dict(mount_dirs, modes):
    """Create the mounting dict.

    :param mount_dirs: List[str], The dirs to mount.
    :param modes: List[str], The mount modes.

    :returns:
        dict, The mounting dict in the form {'external_loc', {'bind': 'internal_loc', 'mode': 'r[ow]'}}
    ."""
    mounts = {}
    for mount, mode in zip(mount_dirs, modes):
        mounts[mount] = {"bind": mount, "mode": mode}
    return mounts