Rust

fix: remove unsed import, fix typo and update function docs #46

Job	Run time
Check cargo fmt	44s
Check License Header	2m 11s
linux build test	3m 59s
build with wasm-pack	3m 13s
cargo test (macos-aarch64)	13m 33s
Verify MSRV (Min Supported Rust Version)	9m 21s
Verify Vendored Code	49s
cargo check no default features	7m 57s
cargo test (amd64)	11m 15s
cargo test datafusion-cli (amd64)	4m 36s
cargo doc	4m 22s
cargo check datafusion	4m 49s
cargo check functions	1m 33s
cargo test doc (amd64)	17m 55s
cargo examples (amd64)	14m 17s
Run sqllogictest with Postgres runner	4m 11s
verify benchmark results (amd64)	8m 11s
clippy	6m 55s
check configs.md and ***_functions.md is up-to-date	3m 48s
check Cargo.toml formatting	2m 56s
cargo test hash collisions (amd64)	15m 39s
cargo test pyarrow (amd64)	2m 58s
	2h 25m 12s

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