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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 set(self, item_name, item_value):
 		""" 		Sets the value of an option in the configuration. 		:param str item_name: The name of the option to set. 		:param item_value: The value of the option to set. 		"""

		if self.prefix:
			item_name = self.prefix + self.seperator + item_name
		item_names = item_name.split(self.seperator)
		item_last = item_names.pop()
		node = self._storage
		for item_name in item_names:
			if not item_name in node:
				node[item_name] = {}
			node = node[item_name]
		node[item_last] = item_value
		return