Sorry for the late reply.
--tuple = (x,
Put the x on its own line, like this:
Now the x, y and z line up.
Start the long expression on the line after the variable, indenting one additional level from that which the variable is indented at. If you break up the long expression onto multiple lines, indent them the same as the first line of the long expression, unless you want to add more for clarity of sub-expressions. The resulting paragraph of code will still resemble the similar paragraphs y and z.
Or, keep the long expression on a single line and let the editor's word wrap handle it.