Evaluate EVAL-EXPRESSION-ARG and print value in the echo area.
When called interactively, read an Emacs Lisp expression and
Value is also consed on to front of the variable `values'.
Optional argument EVAL-EXPRESSION-INSERT-VALUE non-nil (interactively,
with prefix argument) means insert the result into the current buffer
instead of printing it in the echo area. Truncates long output
according to the value of the variables `eval-expression-print-length'
If `eval-expression-debug-on-error' is non-nil, which is the default,
this command arranges for all errors to enter the debugger.