Exercise · beginner · 15 min

Keep identifiers as text and parse yes/no flags

Member IDs and postcodes have leading zeros that must survive, and the opt-in flag arrives as Y, yes, TRUE or 1. Parse the flag to a real boolean without guessing.

The rules

These rules decide what a correct result is. Your answer is checked on this dataset and on hidden datasets that follow the same rules.

Input
  members(member_id, postcode, opted_in) — text. member_id is unique and always present.

Rules
  member_id and postcode are identifiers: keep them as text exactly as given, except that postcode has
  ASCII whitespace removed at both ends. Never convert them to numbers (00123 must stay 00123).
  opted_in: remove ASCII whitespace at both ends, then lowercase, then:
    y, yes, true, 1   → true
    n, no, false, 0   → false
  Quarantine with reason bad_flag when opted_in is missing or anything else (a missing answer is not "no").

Outputs (row order does not matter)
  clean(member_id text, postcode text, opted_in bool)
  exceptions(member_id text, reason text)

The data

members · 17 rows, first 12 shown

member_id	postcode	opted_in
008417	98506·	true
000002	·02139·	maybe
002939	missing	0
015246	·51389	y
077927	·08222	N
092803	30041	true
085051	·12134·	N
000001	00501	yes
004197	·52402	true
016386	·46532·	no
016648	·20460	yes
078978	missing	no

What you practise

identifiers
booleans
mappings
type conversion

Your answer is also checked on hidden datasets generated from the same rules.

Download this dataset (CSV) with its data dictionary