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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 appendChild(self, child):
 		""" 		Add a child to this element. The child's parentNode 		attribute is updated, too. 		"""

		self.childNodes.append(child)
		child.parentNode = self
		self._verifyChildren(len(self.childNodes) - 1)
		return child