//          must have a single output (these operations are typically
//          placeholders created for the sole purpose of representing
//          an input. We can relax this constraint if there are
//          compelling use cases).
//          - If an array is given (`num_opers` >= 0), all operations
//          in it will become part of the function. In particular, no
//          automatic skipping of dummy input operations is performed.

/// that plugins provide (some are mandatory, some are optional, with or without
/// a default implementation).
///
/// Each plugin implements the operations that are supported and TensorFlow will
/// properly handle the cases when an operation is not supported (i.e., return
/// the corresponding `Status` value).
///
/// REQUIRED OPERATIONS: All required operations are marked as such, including