as.lazy                 Convert an object to a lazy expression or lazy
                        dots.
interp                  Interpolate values into an expression.
lazy_                   Capture expression for later lazy evaluation.
lazy_dots               Capture ... (dots) for later lazy evaluation.
lazy_eval               Evaluate a lazy expression.
make_call               Make a call with 'lazy_dots' as arguments.
missing_arg             Generate a missing argument.
