// modification of the graph can increase the number of control
// outputs.  Returns the number of control outputs (should match
// TF_OperationNumControlOutputs(oper)).
TF_CAPI_EXPORT extern int TF_OperationGetControlOutputs(
    TF_Operation* oper, TF_Operation** control_outputs,
    int max_control_outputs);

// TF_AttrMetadata describes the value of an attribute on an operation.
typedef struct TF_AttrMetadata {