Python had no sibling for the Rust `fetch_btcusdt` data-generator —
adding it closes the "fetch (data-gen)" cell for Python and lets users
without a Rust toolchain regenerate the bundled BTCUSDT datasets.
* examples/python/fetch_btcusdt.py — uses only the standard library
(urllib.request + json + csv); same pagination strategy as the Rust
version (paginate backwards via `endTime`, drop the in-progress
bucket, sort and trim to the configured target). Applies the same
OHLC validity check the Rust `Candle::new` constructor enforces
(finite fields, high >= low/open/close, low <= open/close,
volume >= 0) so a malformed kline is skipped rather than written.
* Number formatting matches Rust's `f64` Display: shortest round-trip,
no trailing `.0` for whole-number floats. Verified by running the
script and `git diff`-ing against the checked-in dataset: every row
older than the run is byte-identical to Rust's output; the diff only
shows the most recent ~24 hours where Binance has produced fresh
candles since the original snapshot.
examples/README.md gains the new row.
kingchenc