code: def radius_hydraulic(Width, DistCenter, openchannel):
      
      ut.check_range([Width, ">0", "Width"], [DistCenter, ">0", "DistCenter"],
                     [openchannel, "boolean", "openchannel"])
      if openchannel:
          return (Width*DistCenter) / (Width + 2*DistCenter)
          # if openchannel is True, the channel is open. Otherwise, the channel
          # is assumed to have a top.
      else:
          return (Width*DistCenter) / (2 * (Width+DistCenter))
docs: Return the hydraulic radius.
  
      Width and DistCenter are length values and openchannel is a boolean.