* returns the product of all given arguments. Arguments must evaluate to numeric
values. mult is an alias for this function.
(* 1 2 3)➜6(* 1 1.5)➜1.5
expris 1 or more expressions
* evaluates each of the given expressions in sequence. If an expression returns
an error, * returns that error and stops evaluating further expressions.
All values are multiplied together and the final product is returned.
* uses one scope per expression, so nothing is shared (like variables) between
expressions, and nothing is leaking out.