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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 _SetYaraRules(self, yara_rules_string):
 """Sets the Yara rules. Args: yara_rules_string (str):
 unparsed Yara rule definitions. """

    if not yara_rules_string:
      return

    analyzer_object = analyzers_manager.AnalyzersManager.GetAnalyzerInstance(
        'yara')
    analyzer_object.SetRules(yara_rules_string)
    self._analyzers.append(analyzer_object)