def _get_from_onclick(node, index):
    """Private function to grab a value in the "`onclick`" attribute.

    Grabs the value in the specified index of the "`onclick`" attribute
    of a selectolax `Node`.

    Args:
        node (:class:`Node`): A `Node` containing the "`onclick`" attribute.
        index (:obj:`int`): The index of the value to grab.
    
    Returns:
        :obj:`str`: The value found within the "`onclick`" attribute,
        or `None` if it was not found.
    """

    if node and 'onclick' in node.attributes:
        onclick_split = node.attributes['onclick'].split(',')
        if len(onclick_split) > index:
            return onclick_split[index].strip('\'')
    return None