An hybrid list-tuple concatenation is not allowed >>> []+(1, 2) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: can only concatenate list (not "tuple") to list >>>
hence I was expecting (*) that the following code raises a TypeError : >>> x = [] >>> >>> x += (1, 2) >>> >>> x >>> [1, 2] >>> Any explanation ? (*) as the docs states, the augmented assignment is supposed to perform the concatenation : An augmented assignment (...) performs the binary operation specific to the type of assignment on the two operands (...) -- https://mail.python.org/mailman/listinfo/python-list