anchor.diff:  
   /// Builder for parallel computations with a log.  A computation with a log is
   /// executed in a context with a log for logging individual logged computations.
  +///
  +/// The following computational patterns are supported:
  +///
  +///> ... ; ...
  +///> do ...
  +///> do! ...
  +///> for ... = ... to ... do ...
  +///> for ... in ... do ...
  +///> if ... then ...
  +///> if ... then ... else ...
  +///> let ... = ... in ...
  +///> let! ... = ... | job | logAs
  +///> match ... with ...
  +///> return ...
  +///> return! ... | job | logAs
  +///> try ... finally ...
  +///> try ... with ...
  +///> use ... in ...
  +///> use! ... in ...
  +///> while ... do ...
  +///
  +/// In the above, an ellipsis denotes a computation with a log or an ordinary
  +/// expression.  A computation with a log can directly bind jobs as well as
  +/// computations logged with a user defined identity.  However, updates and
  +/// computations with an implicitly defined identity cannot be bound directly.
   type WithLogBuilder =
     new: unit -> WithLogBuilder
   
  
positive.code:   member inline Return: 'x -> WithLog<'x>
  
    member inline ReturnFrom: WithLog<'x> -> WithLog<'x>
    member        ReturnFrom:   LogAs<'x> -> WithLog<'x>
    member inline ReturnFrom:     Job<'x> -> WithLog<'x>
  
    member inline Bind: WithLog<'x> * ('x -> WithLog<'y>) -> WithLog<'y>
    member        Bind:   LogAs<'x> * ('x -> WithLog<'y>) -> WithLog<'y>
    member inline Bind:     Job<'x> * ('x -> WithLog<'y>) -> WithLog<'y>
  
    member inline Combine: WithLog<unit> * WithLog<'x> -> WithLog<'x>
  
  
negative.code:   val logAs: id: string -> LogAsBuilder
  
    /// Returns a builder for creating a new logged computation.  The computation
    /// is given an automatically determined identity based on the identity of the
    /// surrounding computation.  Otherwise the computation behaves just like a
    /// computation defined with `logAs`.
    val log: LogBuilder
  
    /// Returns a computation that logs the given value as a dependency.
  