Interpreter capabilities supplied by the generated runtime or a test.
pub type Context
pub type Promise(value)
pub fn commit(context: Context, carry: carry) -> Promise(Bool)
pub fn finish(context: Context) -> Promise(Nil)
pub fn reject( context: Context, stage: fn(Context) -> Promise(value), ) -> Promise(Nil)
pub fn resolve(value: value) -> Promise(value)
pub fn then( value: Promise(a), next: fn(a) -> Promise(b), ) -> Promise(b)