# in?
Check if a value exists in a list or set.
## Syntax
[in? $collection $value]
## Examples
[in? @{ 1 2 3 } 2] # true
[in? @{ 1 2 3 } 5] # false
[in? ^{ "a" "b" } "a"] # true
## Returns
Boolean.
## See Also
`contains`, `find`, `any?`, `filter`