anchor.diff:         ['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
   
  
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
            string = ""
  
negative.code:     
    end function is_protein
  
    subroutine fasta_string2seq(string,set,seq,err)
      ! read a sequence, return an array of integer
      character(len=*), intent(in)  :: string
      character(len=*), intent(in)  :: set
      integer,          intent(out) :: seq(:)
      integer,          intent(out) :: err
      integer :: i
  
      seq = [(index(trim(set),string(i:i)), i=1,len_trim(string))]
      
    end subroutine fasta_string2seq
  
  