support for magic node names using `varnames`

[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (fdb193f) 90.99% compared to head (78ca19b) 91.01%.

Files	Patch %	Lines
zntrack/utils/__init__.py	88.88%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #776 +/- ## ========================================== + Coverage 90.99% 91.01% +0.01% ========================================== Files 25 25 Lines 2032 2047 +15 Branches 964 974 +10 ========================================== + Hits 1849 1863 +14 - Misses 183 184 +1 ``` | [Flag](https://app.codecov.io/gh/zincware/ZnTrack/pull/776/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zincware) | Coverage Δ | | |---|---|---| | [fulltest](https://app.codecov.io/gh/zincware/ZnTrack/pull/776/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zincware) | `86.76% <94.11%> (+0.04%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zincware#carryforward-flags-in-the-pull-request-comment) to find out more.

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