The names in an argument list can be back-quoted non-standard names
(see ‘backquote’).
If value
is missing, NULL
is returned. If it is a
single expression, the value of the evaluated expression is returned.
(The expression is evaluated as soon as return
is called, in
the evaluation frame of the function and before any
on.exit
expression is evaluated.)
If the end of a function is reached without calling return
, the
value of the last evaluated expression is returned.