// could contain the op type and other attributes.
typedef struct TF_AbstractOp TF_AbstractOp;

// Stores a function representation that can be used for execution or for
// setting functional attributes of other composite ops e.g. control flow.
typedef struct TF_AbstractFunction TF_AbstractFunction;

// This allows the client to swap the implementation of the tracing engine.
// Any future call to TF_CreateFunction will use the implementation defined
// here.

// Get the number of control inputs to an operation.
TF_CAPI_EXPORT extern int TF_OperationNumControlInputs(TF_Operation* oper);

// Get list of all control inputs to an operation.  `control_inputs` must
// point to an array of length `max_control_inputs` (ideally set to
// TF_OperationNumControlInputs(oper)).  Returns the number of control
// inputs (should match TF_OperationNumControlInputs(oper)).

    // can do its work.
    //
    // Rather than re-entering and delegating Accumulate like this, we could
    // instead allow ForwardAccumulator some control over the current tape set
    // (so it can deactivate itself and activate its GradientTape). Currently
    // that is managed by the language binding and would require relatively
    // messy callbacks.