def find_available_path(from_list: list):
    """
    Function to identify non empty items from nested list

    Parameters
    ----------
    from_list : list
        Nested list containing None and not None entries.

    Returns
    -------
    available_item_list: list
        1D list

    >>> relative_paths = ['spec.json', [None, None, None, [None, None, None, None], None, \
['directory2/directory22/spec.json', None, None, None, None]], ['directory1/spec.json', \
[None, None, None, None], None, None, [None, None, None, None], None, None]]

    >>> find_available_path(relative_paths)
    ['spec.json', 'directory2/directory22/spec.json', 'directory1/spec.json']
    """
    available_item_list = []
    for item in from_list:
        if isinstance(item, list):
            ret_item = find_available_path(item)
            if ret_item:
                available_item_list.extend(ret_item)
        elif isinstance(item, str):
            available_item_list.append(item)
    return available_item_list