Searching `A_mul_B`

in Julia Doc gives me the following results:

```
Base.A_mul_Bc(Function)
Base.A_mul_Bt(Function)
Base.LinAlg.A_mul_B!(Function)
...
```

So I wonder why `A_mul_Bc`

and `A_mul_Bt`

belong to `Base`

, while `A_mul_B!`

lives in Base.LinAlg? Thanks!