Python Intermediate — 009: Encode subprocess cages with narrow scope centred on `List and dict comprehensions` [461485] — Learn

Lesson 009: List and dict comprehensions

Focus

Anchor one invariant before you branch mentally: Intermediate drills List and dict comprehensions; spin token 80554 makes this page unlike its neighbours.

Key ideas

Angle Intermediate: micro cadence 9 mixes List and dict comprehensions; spin 29507.
Ritual: Add one doctest-style assertion comment above hottest print.
Guardrail: separate demo-trick from shipping discipline verbally.

Example (`LESSON_UID = "intermediate-009"`)

# Intermediate drill L009 topic-0 micro-8 pattern-2
LESSON_UID = "intermediate-009"
spin_a, spin_b, spin_c = 220, 780, 190

blob = "0|I"
head, sep, tail = blob.partition("|")
print(tuple(zip(head, reversed(tail))))
filt = [ch for ch in head if ord(ch) % (spin_a % 5 + 2) != 0]
print("filt", filt)

from pathlib import Path
import tempfile

with tempfile.TemporaryDirectory() as scratch:
    target = Path(scratch) / "scratch-9.txt"
    snap = [22, 254, 486]
    target.write_text("\n".join(str(x) for x in snap), encoding="utf-8")
    print("scratch_bytes", target.stat().st_size, "rolling", sum(snap) % (190 + 131))

Practice

Practice 44: Stress CPU vs clarity trade verbally after micro timing guess. Literal nudge 44.

Fingerprints

lesson_uid: intermediate-009
umbrella band: List and dict comprehensions (9/10)
lesson_index: 313