# Documentation of \`{!Foo}?

**URL:** <https://discourse.rocq-prover.org/t/documentation-of-foo/129>\
**Category:** Using Rocq\
**Created:** [February 22, 2019, 2:41pm UTC](https://discourse.rocq-prover.org/t/documentation-of-foo/129 "2019-02-22T14:41:54Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![ejgallego](https://sea1.discourse-cdn.com/flex001/user_avatar/discourse.rocq-prover.org/ejgallego/32/10_2.png) [@ejgallego](https://discourse.rocq-prover.org/u/ejgallego)\
**Post date:** [February 23, 2019, 12:40am UTC](https://discourse.rocq-prover.org/t/documentation-of-foo/129/4 "2019-02-23T00:40:31Z")

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This is an example @JasonGross, why this is useful I have no idea:

```auto
Class M (n : nat).
Definition equiv1 `{M} : Type. Admitted.
Fail Definition equiv2 `{!M} : Type.
Generalizable Variables n.
Definition equiv3 `{!M n} : Type. Admitted.

```

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