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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 CheckIfCanStartClientFlow(self, username, flow_name):
 """Checks whether a given user can start a given flow."""

    del username  # Unused.

    flow_cls = flow.GRRFlow.GetPlugin(flow_name)

    if not flow_cls.category:
      raise access_control.UnauthorizedAccess(
          "Flow %s can't be started via the API." % flow_name)