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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def is_main_variation(self) -> bool: """ Checks if this node is the first variation from the point of view of its parent. The root node is also in the main variation. """

        if not self.parent:
            return True

        return not self.parent.variations or self.parent.variations[0] == self