anchor.diff:    subroutine fasta_init(data_type)
       character(len=*), intent(in) :: data_type
       ! set the aa -> class mapping
  -    integer :: k,nn
  +    integer :: k
       
       aamap = 0
       select case(data_type)
       case('protein')
          do k = 1,21
  -          nn = iachar(protein_alphabet(k))
  -          aamap(nn) = k
  +          aamap(iachar(protein_alphabet(k))) = k
          end do
       case('nuc_acid')
          do k = 1,6
  -          nn = iachar(nuc_acid_alphabet(k))
  -          aamap(nn) = k
  +          aamap(iachar(nuc_acid_alphabet(k))) = k
          end do
       end select
       
  
positive.code:     logical :: res
  
      res = .false.
      if (verify(string,protein_set) == 0) res = .true.
      
    end function is_protein
  
  
negative.code:   implicit none
    private 
    public :: protein_alphabet
    public :: nuc_acid_alphabet
    public :: fasta_read
    character(len=1) :: protein_alphabet(21) = &
         ['A','C','D','E','F','G','H','I','K',&
  