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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 to_array(self):
 """ Serializes this ChatPhoto to a dictionary. :return: dictionary representation of this object. :rtype: dict """

        array = super(ChatPhoto, self).to_array()
        array['small_file_id'] = u(self.small_file_id)  # py2: type unicode, py3: type str

        array['big_file_id'] = u(self.big_file_id)  # py2: type unicode, py3: type str

        return array