Parameters
        ----------
        dna : bytearray
            dna sequence to be reverse complemented

def rev_comp(dna):
        """
        Parameters
        ----------
        dna : bytearray
            dna sequence to be reverse complemented
        """
        
        i2 = len(dna) - 1
        
        l = len(dna) // 2
        
        for i in range(0, l):
            b = DNA_COMP_DICT[dna[i]]
            dna[i] = DNA_COMP_DICT[dna[i2]]
            dna[i2] = b
            i2 -= 1