Listify converts a potential array or slice into a slice of empty interfaces, returning an error if 'array' is not an array/slice.

ListifyOrPanic functions like Listify, but will panic instead of returning an error.

Optional extracts the argument from args at the given offset if len(args) > offset, returning the specified default if args is not long enough.

OptionalUntyped is a variation of Optional that is liberal in the type of argument array that it accepts, using ListifyOrPanic to convert any array/slice.

Sole extracts the optional sole argument from args if len(args) == 0, returning the specified default if args is empty.

SoleUntyped is a variation of Sole that is liberal in the type of argument array that it accepts, using ListifyOrPanic to convert any array/slice.