I'd like my emacs v25.3.1 running on Mac OS X to have a mouse middle button functionality that copies what you mouse middle on to the insertion point in your buffer. This is great when writing code and you want to quickly grab a section of code already in your file by pointing with your mouse. This is the way the old Lisp Machines worked with Zmacs and the ZWEI editor. You click a point and it copies an sexp you point to or you click drag to specify an exact range of characters to copy, or you click at end of line to copy a whole line.
I've had doing this on my own, but it always breaks going to a new version of emacs, so it would be nice if there was built-in code to do this or an add-on that is supported.
I found Mouse Copy but that project appears untouched since 2012.