assign_allocatable_I1P_3D Subroutine

   subroutine assign_allocatable_I1P_3D(lhs, rhs, msg, verbose)
   !< Assign CPU variable with memory checking (kind I1P, rank 3).
   !< Variable is returned not allocated if right hand side is not allocated.
   !<
   !<```fortran
   !< use penf
   !< integer(I1P), allocatable :: a(:,:,:), b(:,:,:)
   !< allocate(b(1:1,1:2,1:3))
   !< call assign_allocatable(a, b)
   !< print*, allocated(a)
   !<```
   !=> T <<<
   integer(I1P), allocatable, intent(inout)        :: lhs(:,:,:) !< Left hand side of assignement.
   integer(I1P), allocatable, intent(in)           :: rhs(:,:,:) !< Right hand side of assignement.
   character(*),              intent(in), optional :: msg        !< Message to be printed in verbose mode.
   logical,                   intent(in), optional :: verbose    !< Flag to activate verbose mode.

   if (allocated(lhs)) deallocate(lhs)
   if (allocated(rhs)) then
      if (size(rhs, dim=1)*size(rhs, dim=2)*size(rhs, dim=3)>0) then
         call allocate_variable(var=lhs,                                                  &
                                ulb=reshape([lbound(rhs,dim=1),ubound(rhs,dim=1),         &
                                             lbound(rhs,dim=2),ubound(rhs,dim=2),         &
                                             lbound(rhs,dim=3),ubound(rhs,dim=3)],[2,3]), &
                                msg=msg, verbose=verbose)
         lhs = rhs
      endif
   endif
   endsubroutine assign_allocatable_I1P_3D