anchor.diff:               allocate(seq(nv),stat=err)
                allocate(seqs(nv,ns),stat=err)
             end if
  -          call fasta_string2seq(string,seq,error_code,error_string)
  +          call fasta_string2seq(string,symbols_set,seq,error_code)
             if (error_code > 0) return
             seqs(:,k) = seq
             string = ""
  
positive.code:              allocate(seq(nv),stat=err)
               allocate(seqs(nv,ns),stat=err)
            end if
            call fasta_string2seq(string,seq,error_code,error_string)
            if (error_code > 0) return
            seqs(:,k) = seq
            exit 
  
negative.code: 
      if (nnuc > nprot) then
         data_type = 'nuc_acid'
         symbols_set = nuc_acid_set
      else
         data_type = 'protein'
         symbols_set = protein_set
      end if
  
      string = ""
  