def is_storage(url, storage=None):
    """
    Check if file is a local file or a storage file.

    File is considered local if:
        - URL is a local path.
        - URL starts by "file://"
        - a "storage" is provided.

    Args:
        url (str): file path or URL
        storage (str): Storage name.

    Returns:
        bool: return True if file is local.
    """
    if storage:
        return True
    split_url = url.split('://', 1)
    if len(split_url) == 2 and split_url[0].lower() != 'file':
        return True
    return False
