set
or get
. If no set
occurs
between remove
and get
, the variable is reinitialized with the
value originally passed to make
; see
remove(...).wrap obj
wraps the reference obj
into an option type:Some x
if obj
is not null
;None
if obj
is null
.unwrap obj
unwraps the option obj
into a bare reference:Some x
is mapped to x
;None
is mapped to null
.