Function returnsArg

returnsArg<Arg, Self>(idx): ((this: Self, ...args: Arg[]) => Arg | undefined)
Creates a function that returns one of its arguments.
Type Parameters
- Arg
  The type of returned argument.
- Self = any
  The self type of the returned function.
Parameters
- idx: number
  The index of the arguments to use.
Returns ((this: Self, ...args: Arg[]) => Arg | undefined)
A function that returns one of its arguments.
- - (this, ...args): Arg | undefined
  - Parameters
    - this: Self
    - Rest...args: Arg[]
    Returns Arg | undefined
Example: Usage
```
import { returnsArg } from "@std/testing/mock";
import { assertEquals } from "@std/assert";

const func = returnsArg(1);
assertEquals(func(1, 2, 3), 2);
```
- Defined in testing/mock.ts:1668