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Symmetry of error throwing and handling.


Symbol: |->
Translated to JavaScript try-catch.

First parameter is catch function.
Other parameters are try lines.
Unlike JavaScript try-catch operator |-> in Una always returns some value and it doesn't have finally block.


= getName null
getName ()
-> error
console.log error

If you need to run async code use <-- instead of <- in try or --> instead -> in catch:

getNameAsync ()
--> error
console.log error

Throw error#

Symbol: <-|
Translated to JavaScript throw.


= addOneToNumber -> number
?! (isNaN number)
<-| "number is not valid"
+ number 1