Pyth, an extremely concise language.
= and ~ now allow an implicit Q if they are not followed by any variables for the rest of the program.
mQ=h, the = assigns the result of h, which expands to hQ to Q. Thus, with an input of 2, the output is [3, 3, 3].J and K now define assignment expressions until an assignment expression is complete, since the associated variables are not defined until that point.
J+J4*J3J, the first J defines an assignment expression. + is part of that expression, J is part of that expression and defines another assignment expression. That inner assignment gives J the value 4. Now, J is defined, and so it is treated as a variable in the expression *J3. Then, the final J is an expression of its own, and prints out J's new value at this point, 16.