print_section Subroutine

  subroutine print_section(self, unit, retain_comments, pref, iostat, iomsg)
  !< Print data with a pretty format.
  class(section), intent(in)            :: self            !< Section data.
  integer(I4P),   intent(in)            :: unit            !< Logic unit.
  logical,        intent(in)            :: retain_comments !< Flag for retaining eventual comments.
  character(*),   intent(in),  optional :: pref            !< Prefixing string.
  integer(I4P),   intent(out), optional :: iostat          !< IO error.
  character(*),   intent(out), optional :: iomsg           !< IO error message.
  character(len=:), allocatable         :: prefd           !< Prefixing string.
  integer(I4P)                          :: iostatd         !< IO error.
  character(500)                        :: iomsgd          !< Temporary variable for IO error message.
  integer(I4P)                          :: o               !< Counter.

  prefd = '' ; if (present(pref)) prefd = pref
  if (allocated(self%sname)) write(unit=unit, fmt='(A)', iostat=iostatd, iomsg=iomsgd)prefd//'['//self%sname//']'
  if (allocated(self%options)) then
    do o=1, size(self%options, dim=1)
      call self%options(o)%print(pref=prefd//'  ', iostat=iostatd, iomsg=iomsgd, unit=unit, retain_comments=retain_comments)
    enddo
  endif
  if (present(iostat)) iostat = iostatd
  if (present(iomsg))  iomsg  = iomsgd
  endsubroutine print_section