Nvidia GPUs".
    enabled_by_default: boolean for default behavior.
    question: optional string for how to ask for user input.
    yes_reply: optional string for reply when feature is enabled.
    no_reply: optional string for reply when feature is disabled.

  Returns:
    boolean value of the variable.

  Raises:

//                 names - "[a-z][a-z0-9_]*". In the latter case,
//                 names for outputs will be generated automatically.
//  opts - various options for the function, e.g. XLA's inlining control.
//  description - optional human-readable description of this function.
//  status - Set to OK on success and an appropriate error on failure.
//
// Note that when the same TF_Output is listed as both an input and an output,