[nawaaaaaAaar]

Summary

Restore the documented integer form of in-place multiplication (styles *= n) while preserving the existing Cycler-product behavior.

Ordinary integer multiplication works for positive counts, but the in-place form raises TypeError. Testing zero/negative counts exposed a prerequisite: composing/copying empty cycles loses their declared keys or raises StopIteration. Preserve key metadata independently of the first generated row and reuse ordinary multiplication for the in-place operation, retaining object identity.

Before/after

Unchanged upstream: d1737eb0a42bd451e8770cef245ebe60ebb36bfc.

from cycler import cycler
styles = cycler(color=["red", "blue"])
styles *= 2  # Before: TypeError; after: repeated styles, same object

The final regression selection yields 19 failures and two passes before the implementation change, then 21 passes afterward. Coverage includes base/summed/product cycles, integer counts -2/0/1/2/3, object identity, equality, key metadata, representation and by-key values.

Verification

• Full suite: 49 passed on Python 3.9.25 with two xdist workers and Python 3.12.13; no skips.
• Both runs report 99% combined statement/branch coverage.
• Source distribution and wheel build with python -m build --no-isolation.
• git diff --check passes.
• Full flake8 and project-pinned mypy 1.5.1 checks pass. Final workflow inspection caught the separate reviewdog lint/type workflow; a narrow helper correction preserves the existing annotated iterable input contract as well as Cycler metadata.
• Linux-only local checks; Python 3.8 and other supported versions/platforms were not all tested. Hosted results remain separate.

Assistance

Prepared using AI assistance for investigation, implementation and tests. No personal account-owner review, provenance attestation or maintainer acceptance is asserted. This is one coherent multiplication correctness change, including the empty-result prerequisite, not separate PRs for the same operation.
Fixes #109.

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[timhoffm]

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