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Concepts·Certified Entry-Level Python Programmer

Python Generators and yield

PCEP names generators in passing under objective 4.1 and asks little about them; PCAP's comprehension and closure material assumes you know what a lazy sequence is. This guide fills that gap. A generator is a function containing `yield`: calling it runs none of the body, and each `next()` runs it as far as the next `yield` and then freezes it there. Seeing that interleaving is the only way it becomes obvious.

Functions and Scope Guide 22 of 26 Intermediate

Written against the versions above. `yield` has been in Python since 2.2 and generator expressions since 2.4. Nothing here is version-sensitive. `yield from` and `send()` exist and are examined by neither exam.

One machine, and any shell with Python 3 will do - these exams test the language, not a distribution.
Server NameIP AddressOSRolesCPURAMHDD
RUNNER01192.168.0.27Ubuntu 26.04 LTSPython 3.14.4 - the only machine this path needs2 Core4 GB50 GB

Before you start

  1. yield instead of return

  2. Running off the end

  3. A generator works anywhere an iterable does

  4. A generator can only be walked once

  5. How little work happens before you ask

  6. The generator expression

  7. What the exams do with generators

Official sources

← All PCEP guides