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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 prepend(self, node):
 """Prepend a statement to the current statement. Note that multiple calls to prepend will result in the last statement to be prepended to end up at the top. Args: node: The statement to prepend. Raises: ValueError: If the given node is not a statement. """

    if not isinstance(node, grammar.STATEMENTS):
      raise ValueError
    self.to_prepend[-1].appendleft(node)