Ptr returns a pointer to the value.

PtrDefToNil returns a pointer to the value, or nil if "def".

PtrZeroToNil returns a pointer to the value, or nil if false.

SafeIndex returns "s[i]" if possible, and false otherwise.

SafeIndexDef returns "s[i]" if possible, and "def" otherwise.

SafeIndexPtr returns "s[i]" if possible, and nil otherwise.

Val returns the pointer value, defaulting to false if nil.

ValDef returns the pointer value, defaulting to "def" if nil.