I want to join two shapes in TikZ, like in the example below. As it can be seen, I use an arrow and a rectangle to create an arrow with "two inputs". I did not find a simple way to achieve this in LaTeX using predefined shapes, is there any? The black color in below image is simply for visualisation, I would like to have a white fill and a black outline.
I am looking for something like the following pseudo code:
\node (a) [arrow, draw] at (0,0);
\node (r) [rectangle, draw] at (0,0);
\join {a,r};