Using dunder methods to making work in REPL easier.

[BjornFJohansson]

Every dunder method in Python, summarized in the table below.
We use "+" / add() in Dseq to signify double stranded ligation when two phosphodiester bonds are formed. Other dunder methods could be overridden for other kinds of manipulation.

for instance "~obj" / invert could for example return the reverse complement of the sequence.

Operator	Dunder method	Reverse	In-place
+	__add__()	__radd__()	__iadd__()
-	__sub__	__rsub__	__isub__	✅
*	__mul__	__rmul__	__imul__
/	__truediv__	__rtruediv__	__itruediv__	✅
//	__floordiv__	__rfloordiv__	__ifloordiv__	✅
%	__mod__	__rmod__	__imod__	✅
divmod(a, b)	__divmod__	__rdivmod__	—	✅
**	__pow__	__rpow__	__ipow__
+a	__pos__(self)	—	—
-a	__neg__(self)	—	—
abs(a)	__abs__(self)	—	—
round(a)	__round__(self, n)	—	—
@	__matmul__	__rmatmul__	__imatmul__
&	__and__	__rand__	__iand__	✅
`	`	__or__	__ror__
^	__xor__	__rxor__	__ixor__
<<	__lshift__	__rlshift__	__ilshift__
>>	__rshift__	__rrshift__	__irshift__
~a	__invert__(self)	—	—