code: def render(self):
          
          if not self.available():
              return ""
  
          mtool = api.get_tool("portal_membership")
          member = mtool.getAuthenticatedMember()
          roles = member.getRoles()
          allowed = "LabManager" in roles or "Manager" in roles
  
          self.get_failed_instruments()
  
          if allowed and self.nr_failed:
              return self.index()
          else:
              return ""
docs: Render the viewlet