def split_path(path):
    """
    Normalise S3 path string into bucket and key.

    Parameters
    ----------
    path : string
        Input path, like `s3://mybucket/path/to/file`

    Examples
    --------
    >>> split_path("s3://mybucket/path/to/file")
    ['mybucket', 'path/to/file']
    """
    if path.startswith('s3://'):
        path = path[5:]
    if '/' not in path:
        return path, ""
    else:
        return path.split('/', 1)