anchor.diff:      !pressure (at inlet and outlets)
       !flow (flow at inlet pressure at outlet).
   
  -vessel_type='elastic_g0_beta'
  +
   mechanics_type='linear'
   
   if (vessel_type.eq.'rigid') then
  
positive.code: end subroutine calculate_ppl
  
  end module pressure_resistance_flow
  
  
negative.code: 
    !Interfaces
    private
    public evaluate_prq,calculate_ppl
  contains
  !###################################################################################
  !
  !*evaluate_PRQ:* Solves for pressure and flow in a rigid or compliant tree structure
    subroutine evaluate_prq(mesh_type,vessel_type,grav_dirn,grav_factor,bc_type,inlet_bc,outlet_bc)
    !DEC$ ATTRIBUTES DLLEXPORT,ALIAS:"SO_EVALUATE_PRQ" :: EVALUATE_PRQ
      use indices
      use capillaryflow,only: cap_flow_ladder
  