Function interp_hashset 

fn interp_hashset(
    _args: &[RValue],
    _named: &[(String, RValue)],
    context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Create an empty HashSet (unordered unique-element set).

Returns an integer ID with class “hashset”. Use hashset_add(), hashset_has(), etc. to manipulate it.

@return integer scalar with class “hashset”