loop Function

  function loop(self, option_pairs) result(again)
  !< Loop returning option name/value defined into section.
  class(section),                intent(in)  :: self            !< Section data.
  character(len=:), allocatable, intent(out) :: option_pairs(:) !< Couples option name/value [1:2].
  logical                                    :: again           !< Flag continuing the loop.
  integer(I4P), save                         :: o=0             !< Counter.

  again = .false.
  if (allocated(self%options)) then
    if (o==0) then
      o = lbound(self%options, dim=1)
      call self%options(o)%get_pairs(pairs=option_pairs)
      again = .true.
    elseif (o<ubound(self%options, dim=1)) then
      o = o + 1
      call self%options(o)%get_pairs(pairs=option_pairs)
      again = .true.
    else
      o = 0
      again = .false.
    endif
  endif
  endfunction loop