# Description
Prevent a situation where a `def` can't be run due to a poor choice of
name. Related: #6335. Hashtags, numbers and filesizes are no longer
allowed. `alias` check has been moved because previously `alias 123`
would be caught but `alias "123"` would be permitted.
# User-Facing Changes
Some definitions can no longer be made, but because they couldn't be run
previously anyway, it doesn't really matter.
# Tests + Formatting
Don't forget to add tests that cover your changes.
Make sure you've run and fixed any issues with these commands:
- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass
# After Submitting
If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
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