code: def merge_read_pair_seq(self, r1, r2):
          
          
          s1 = r1.pos # + 1
              
          # end of first read
          e1 = s1 + r1.length - 1
      
          # start of second read
          s2 = r2.pos # + 1
          
          e2 = s2 + r2.length - 1
      
          inner = s2 - e1 - 1
      
          if inner >= 0:
              seq = self.dna((r1.chr, s1, e2))
          else:
              # Reads overlap so concatenate the first read with the
              # portion of the second read that is not overlapping
              # (inner is negative so flip sign for array indexing)
              seq = r1.seq + r2.seq[-inner:]
              
          return seq
docs: Merge the sequence of two reads into one continuous read either
          by inserting the missing DNA, or joining on the common sequence.
          
          Parameters
          ----------
          r1 : libsam.Read
              Read 1
          r2 : libsam.Read
              Read 2