raise

        # Fiber.raise

(from ruby core)
---
    fiber.raise                                 -> obj
    fiber.raise(string)                         -> obj
    fiber.raise(exception [, string [, array]]) -> obj

---

Raises an exception in the fiber at the point at which the last
`Fiber.yield` was called. If the fiber has not been started or has
already run to completion, raises `FiberError`. If the fiber is
yielding, it is resumed. If it is transferring, it is transferred into.
But if it is resuming, raises `FiberError`.

With no arguments, raises a `RuntimeError`. With a single `String`
argument, raises a `RuntimeError` with the string as a message. 
Otherwise, the first parameter should be the name of an `Exception`
class (or an object that returns an `Exception` object when sent an
`exception` message). The optional second parameter sets the message
associated with the exception, and the third parameter is an array of
callback information. Exceptions are caught by the `rescue` clause of
`begin...end` blocks.