# Optional input path

**URL:** <https://community.seqera.io/t/optional-input-path/1655>\
**Category:** Ask for help\
**Tags:** nf-core\
**Created:** [January 24, 2025, 7:21pm UTC](https://community.seqera.io/t/optional-input-path/1655 "2025-01-24T19:21:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![sstrong99](https://dub1.discourse-cdn.com/flex013/user_avatar/community.seqera.io/sstrong99/32/188_2.png) [@sstrong99](https://community.seqera.io/u/sstrong99)\
**Post date:** [January 24, 2025, 7:21pm UTC](https://community.seqera.io/t/optional-input-path/1655/1 "2025-01-24T19:21:10Z")

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The SAMTOOLS\_STATS nf-core module appears to allow the user to only optionally provide the fasta: [modules/modules/nf-core/samtools/stats/main.nf at 5b33c12fb7b488b39311fd3e8e63d4a73e7475c2 · nf-core/modules · GitHub](https://github.com/nf-core/modules/blob/5b33c12fb7b488b39311fd3e8e63d4a73e7475c2/modules/nf-core/samtools/stats/main.nf#L23C21-L23C56)

but i’m not sure how to provide that channel input so that the code will recognize it as a falsey value.

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<div class="post-metadata">

**Author:** ![sstrong99](https://dub1.discourse-cdn.com/flex013/user_avatar/community.seqera.io/sstrong99/32/188_2.png) [@sstrong99](https://community.seqera.io/u/sstrong99)\
**Post date:** [January 24, 2025, 10:58pm UTC](https://community.seqera.io/t/optional-input-path/1655/2 "2025-01-24T22:58:59Z")

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I figured out the solution: pass in an empty list. e.g.:

```auto
SAMTOOLS_STATS(ch_bam, [])

```

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<div class="post-metadata">

**Author:** ![system](https://dub1.discourse-cdn.com/flex013/user_avatar/community.seqera.io/system/32/2402_2.png) [@system](https://community.seqera.io/u/system)\
**Post date:** [January 31, 2025, 10:59pm UTC](https://community.seqera.io/t/optional-input-path/1655/3 "2025-01-31T22:59:15Z")

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Closed on January 31, 2025, 10:59pm UTC

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