Checks if this node starts a variation (and can thus have a starting
        comment). The root node does not start a variation and can have no
        starting comment.

        For example, in ``1. e4 e5 (1... c5 2. Nf3) 2. Nf3``, the node holding
        1... c5 starts a variation.

def starts_variation(self) -> bool:
        """
        Checks if this node starts a variation (and can thus have a starting
        comment). The root node does not start a variation and can have no
        starting comment.

        For example, in ``1. e4 e5 (1... c5 2. Nf3) 2. Nf3``, the node holding
        1... c5 starts a variation.
        """
        if not self.parent or not self.parent.variations:
            return False

        return self.parent.variations[0] != self