Fix a bug with subscript assign #469

Job	Run time
Test pre-commit console encoding	31s
Test Python 3.9 (ubuntu-latest)	59s
Test Python 3.10 (ubuntu-latest)	1m 7s
Test Python 3.11 (ubuntu-latest)	1m 1s
Test Python 3.12 (ubuntu-latest)	1m 9s
Test Python 3.13 (ubuntu-latest)	1m 10s
Test Python 3.9 (windows-latest)	2m 38s
Test Python 3.10 (windows-latest)	2m 32s
Test Python 3.11 (windows-latest)	2m 58s
Test Python 3.12 (windows-latest)	3m 18s
Test Python 3.13 (windows-latest)	3m 38s
Test Python 3.9 (macOS-latest)	1m 17s
Test Python 3.10 (macOS-latest)	1m 16s
Test Python 3.11 (macOS-latest)	1m 0s
Test Python 3.12 (macOS-latest)	53s
Test Python 3.13 (macOS-latest)	58s
	26m 25s

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