code: def headloss_rect(FlowRate, Width, DistCenter, Length,
                    KMinor, Nu, PipeRough, openchannel):
      
      #Inputs do not need to be checked here because they are checked by
      #functions this function calls.
      return (headloss_exp_rect(FlowRate, Width, DistCenter, KMinor).magnitude
                + headloss_fric_rect(FlowRate, Width, DistCenter, Length,
                                     Nu, PipeRough, openchannel).magnitude)
docs: Return the total head loss in a rectangular channel.
  
      Total head loss is a combination of the major and minor losses.
      This equation applies to both laminar and turbulent flows.