anchor.diff:  
       if (nnuc > nprot) then
          data_type = 'nuc_acid'
  +       symbols_set = nuc_acid_set
       else
          data_type = 'protein'
  +       symbols_set = protein_set
       end if
   
       string = ""
  
positive.code:     
    end function is_protein
  
    subroutine fasta_string2seq(string,seq,error_code,error_string)
      ! read a sequence, return an array of integer
      character(len=*), intent(in)  :: string
      integer,          intent(out) :: seq(:)
      integer,          intent(out) :: error_code
      character(len=*), intent(out) :: error_string
      integer :: i,n,ind
      integer :: err
  
      error_string = ''
      n = len_trim(string)
      seq = [(index(protein_set,string(i:i)), i=1,len_trim(string))]
      
    end subroutine fasta_string2seq
  
  
negative.code:        ['A','C','G','T','U','-']
    character(len=kprot) :: protein_set='ACDEFGHIKLMNPQRSTVWY-'
    character(len=knuc)  :: nuc_acid_set='ACGTU-'
    character(len=string_size) :: symbols_set
  
  contains
  
  