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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 mutate_query_from_config(self, sql):
 """Apply config's SQL_QUERY_MUTATOR Typically adds comments to the query with context"""

        SQL_QUERY_MUTATOR = config.get('SQL_QUERY_MUTATOR')
        if SQL_QUERY_MUTATOR:
            username = utils.get_username()
            sql = SQL_QUERY_MUTATOR(sql, username, security_manager, self.database)
        return sql