Execute the region as Lisp code.
When called from programs, expects two arguments,
giving starting and ending indices in the current buffer
of the text to be executed.
Programs can pass third argument PRINTFLAG which controls output:
A value of nil means discard it; anything else is stream for printing it.
Also the fourth argument READ-FUNCTION, if non-nil, is used
instead of `read' to read each expression. It gets one argument
which is the input stream for reading characters.
This function does not move point.
(fn START END &optional PRINTFLAG READ-FUNCTION)