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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 write_skills_data(self, data=None):
 """ Write skills data hash if it has been modified. """

        data = data or self.skills_data
        if skills_data_hash(data) != self.skills_data_hash:
            write_skills_data(data)
            self.skills_data_hash = skills_data_hash(data)