code: def headloss_fric_general(Area, PerimWetted, Vel, Length, Nu, PipeRough):
      
      #Checking input validity - inputs not checked here are checked by
      #functions this function calls.
      ut.check_range([Length, ">0", "Length"])
      return (fric_general(Area, PerimWetted, Vel, Nu, PipeRough) * Length
              / (4 * radius_hydraulic_general(Area, PerimWetted).magnitude)
              * Vel**2 / (2*gravity.magnitude)
              )
docs: Return the major head loss due to wall shear in the general case.
  
      This equation applies to both laminar and turbulent flows.