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In this commit, we close the biggest fidelity gap the simulator had: hidden liquidity only moved when the sender's own payments moved it, so knowledge never went stale and evidence-based routing strategies were unbeatable by construction. Real networks keep churning between a node's sends. Two additions, both opt-in per scenario file. A virtual clock advances simulated time between payments (payment_gap_sec) and per attempt (attempt_sec); the mission control stack behind the lnd baseline is switched onto the same settable clock, so decay half-lives operate over simulated rather than wall-clock time, and candidate routers can read the current time through the new Now() method on SimNetworkView. A background traffic engine executes seeded payments between random node pairs in each gap: naive fee-optimizing senders route along the cheapest public path with no knowledge of hidden balances, retrying around failed edges a bounded number of times, so only the payments that genuinely clear move liquidity, hop by hop, with per-channel conservation. The traffic sequence depends only on its seed, so competing routers face the identical exogenous process, and scenario files without the new sections reproduce their previous results bit for bit. The corpus generator grows a --drift flag that scales traffic volume with network size, and the code-mode reflection prompt now describes the drifting environment neutrally, flagging that the champions' hard liquidity bounds were learned in a static world, without prescribing whether time-awareness is the answer -- that is exp-008's question to settle.
193 lines
8.3 KiB
Python
193 lines
8.3 KiB
Python
#!/usr/bin/env python3
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"""Run GEPA over entire routing algorithms (code candidates).
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The candidate is the full Go source of cmd/routesim/candidate_impl.go. The
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seed is the in-tree simple router; the target to beat is lnd's production
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stack, whose per-example scores are reported alongside for reference.
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"""
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import argparse
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from pathlib import Path
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from gepa.optimize_anything import (
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OptimizeAnythingConfig,
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optimize_adaptive_sequential,
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optimize_anything,
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)
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from codex_lm import CodexLM
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from evaluate_code import REPO, evaluate
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OBJECTIVE = """
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Evolve a Lightning Network routing algorithm (Go source, the complete
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contents of candidate_impl.go) that maximizes payment success rate in a
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network simulator, with fewer retry attempts and lower fees as secondary
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goals. You may redesign the algorithm entirely — probability models,
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splitting strategies, exploration policies — as long as the
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newCandidateRouter contract compiles and the code stays pure routing logic.
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"""
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BACKGROUND = """
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Contract: package main must define
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newCandidateRouter(view routing.SimNetworkView, source route.Vertex,
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localBalances map[uint64]lnwire.MilliSatoshi, spec *routing.SimPaymentSpec)
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(routing.SimRouter, error). The returned router implements
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RequestRoute(amt, inFlightHtlcs) (*route.Route, error) — return an error to
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terminally give up — and ReportAttempt(attemptID, rt, result) error, which
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delivers per-attempt feedback (result.Failure nil = settled; otherwise
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result.FailureSource names the failing node and the failure code tells you
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why: TemporaryChannelFailure = liquidity miss, FeeInsufficient /
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IncorrectCltvExpiry = your route's fees or cltv deltas violate the failing
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node's advertised policy).
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Environment truths worth exploiting:
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- Hidden liquidity is drawn mostly from a BIMODAL distribution: channel
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funds sit almost entirely on one side. A 50/50 assumption is usually
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wrong; a failure at amount a on a channel is strong evidence the whole
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channel is depleted in that direction, and a success means most capacity
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is available.
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- The gossip view exposes per-direction policies (fees, cltv delta,
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min/max htlc) and channel capacities via ForEachNodeDirectedChannel;
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InPolicy on a channel of node N is the policy the OTHER node announced
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toward N (i.e. it governs edges INTO N).
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- Route encoding: amount over channel i is TotalAmount for i=0, else
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Hops[i-1].AmtToForward; fees accumulate backward from the target;
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the final hop needs cltv delta 40.
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- MPP: the runner keeps calling RequestRoute with the remaining amount;
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spec.MaxParts caps concurrent shards; each successful shard reduces the
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remaining amount.
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- Payments per scenario batch run sequentially and liquidity persists, so
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knowledge from earlier payments in the batch transfers.
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- THE NETWORK KEEPS MOVING BETWEEN YOUR PAYMENTS: scenario files may
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enable background traffic, where other participants' payments shift
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hidden liquidity in the (virtual) minutes between your payments, and a
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virtual clock, readable as view.Now(), advances between payments and
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attempts. In such environments, what you learned about a channel k
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payments ago may no longer hold. Whether and how to account for the
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age of evidence is entirely your design choice.
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The current seed is a cheapest-path Dijkstra with failure blacklisting and
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halving splits. Known weaknesses to consider: it ignores capacity when
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choosing among paths (bigger channels succeed more often), it has no
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notion of probability weighting fees vs reliability, it never retries a
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blacklisted channel at lower amounts within a payment, and its shard
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halving is crude.
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Insights from prior successful runs (champions hb1/mx_c3, see
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simulation/champions/), worth building on rather than rediscovering:
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- An explicit BIMODAL PRIOR over amount/capacity works: near-certain for
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tiny amounts (decaying exponential low mode), a logistic cliff as the
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amount approaches capacity, floors/caps around [0.005, 0.985].
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- Per-directed-channel liquidity BELIEFS work well: track lower-OK
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(largest amount proven to pass) and upper-fail (smallest proven to
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fail) bounds plus a confidence-weighted point estimate; return ~0.995
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below lower-OK, ~0 above upper-fail, blend with the prior in between.
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(Caveat: this insight was learned in environments with NO background
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traffic, where old evidence never went stale. Its hard bounds may or
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may not survive in a drifting network.)
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- Retry-at-lower-amount on a failed channel (a lower-retry factor)
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outperforms permanently blacklisting it.
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- Keep the implementation LEAN: past ~800 lines, edits stop compiling
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and progress stalls. Prefer simplifying refactors over accretion.
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"""
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def main() -> None:
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parser = argparse.ArgumentParser()
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parser.add_argument("--corpus", default="corpus")
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parser.add_argument("--name", default="router_code")
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parser.add_argument("--max-evals", type=int, default=None)
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parser.add_argument("--reflection-lm", default="codex:gpt-5.6-sol")
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parser.add_argument("--max-concurrency", type=int, default=4)
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parser.add_argument("--adaptive", action="store_true", default=True,
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help="rotate gepa <-> meta_harness on plateaus")
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parser.add_argument("--no-adaptive", dest="adaptive",
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action="store_false")
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parser.add_argument("--seed-file", default=None,
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help="seed candidate .go file (default: the "
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"in-tree candidate_impl.go). Use a prior "
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"champion to continue evolving from it.")
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args = parser.parse_args()
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corpus = Path(args.corpus)
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trainset = sorted(str(p) for p in (corpus / "train").glob("*.json"))
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valset = sorted(str(p) for p in (corpus / "val").glob("*.json"))
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testset = sorted(str(p) for p in (corpus / "test").glob("*.json"))
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if not trainset or not valset:
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raise SystemExit(f"no corpus at {corpus}; run gen_scenarios.py")
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if args.seed_file:
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seed = Path(args.seed_file).read_text()
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else:
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seed = (REPO / "cmd" / "routesim" / "candidate_impl.go").read_text()
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max_evals = args.max_evals or 20 * len(valset)
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reflection_lm = args.reflection_lm
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if reflection_lm.startswith("codex:"):
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reflection_lm = CodexLM(model=reflection_lm.split(":", 1)[1])
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gepa_config = OptimizeAnythingConfig(
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engine="gepa",
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name=args.name,
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max_evals=max_evals,
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max_concurrency=args.max_concurrency,
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run_dir=f"runs/{args.name}",
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output_dir=f"outputs/{args.name}",
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engine_config={
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"reflection": {
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"reflection_lm": reflection_lm,
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"reflection_minibatch_size": 3,
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},
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"engine": {
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"max_workers": args.max_concurrency,
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"seed": 0,
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},
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},
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)
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if args.adaptive:
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# Rotate between the gepa backend (codex reflection) and the
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# meta_harness agentic proposer (claude CLI) whenever the score
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# plateaus, all drawing from one shared eval budget.
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meta_config = OptimizeAnythingConfig(
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engine="meta_harness",
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name=f"{args.name}_meta",
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run_dir=f"runs/{args.name}_meta",
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)
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result = optimize_adaptive_sequential(
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seed_candidate=seed,
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evaluator=lambda cand, ex: evaluate(cand, ex),
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configs=[gepa_config, meta_config],
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plateau_evals=len(valset) * 3,
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dataset=trainset,
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valset=valset,
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test_set=testset,
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objective=OBJECTIVE.strip(),
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background=BACKGROUND.strip(),
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name=args.name,
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max_evals=max_evals,
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max_concurrency=args.max_concurrency,
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output_dir=f"outputs/{args.name}",
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)
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else:
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result = optimize_anything(
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seed_candidate=seed,
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evaluator=lambda cand, ex: evaluate(cand, ex),
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dataset=trainset,
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valset=valset,
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test_set=testset,
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objective=OBJECTIVE.strip(),
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background=BACKGROUND.strip(),
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config=gepa_config,
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)
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print("=== best candidate ===")
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print(result.best_candidate)
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print("best (val) score:", result.best_score)
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print("held-out test:", result.metadata.get("test_score"),
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"| seed held-out:", result.metadata.get("baseline_test_score"))
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if __name__ == "__main__":
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main()
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