} TF_Output;

// TF_Function is a grouping of operations with defined inputs and outputs.
// Once created and added to graphs, functions can be invoked by creating an
// operation whose operation type matches the function name.
typedef struct TF_Function TF_Function;

// Function definition options. TODO(iga): Define and implement
typedef struct TF_FunctionOptions TF_FunctionOptions;

  ///        matches any single character (not) on the list
  ///   c: matches character c (c != '*', '?', '\\', '[')
  ///   '\\' c: matches character c
  /// character-range:
  ///   c: matches character c (c != '\\', '-', ']')
  ///   '\\' c: matches character c
  ///   lo '-' hi: matches character c for lo <= c <= hi
  ///
  /// Implementations must allocate `entries` to hold all names that need to be