I recently got an email from Jeff Shrager, who said he'd been working hard to solve a mystery about some famous code. Eliza, the chatbot, was built in 1964, and she didn't answer questions like Alexa or Siri. She asked questions. She was a therapist chatbot and quickly became famous after being described in a 1964 paper. But here is the mystery. We're not sure how the original version worked.…