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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 _FetchServerCertificate(self):
 """Attempts to fetch the server cert. Returns: True if we succeed. """

    # Certificate is loaded and still valid.
    if self.server_certificate:
      return True

    response = self.http_manager.OpenServerEndpoint(
        "server.pem", verify_cb=self.VerifyServerPEM)

    if response.Success():
      self.server_certificate = response.data
      return True

    # We failed to fetch the cert, switch to slow poll mode.
    self.timer.SlowPoll()
    return False