Hello everyone,

I have just started to learn about Julia(<:1.0).

Unfortunately, I am not able to understand the use/functionality of Type{T}, for example, in

```
convert(::Type{T}, a::T) where {T<:AbstractArray} = a
```

why cannot we use

```
convert(::T, a::T) where {T<:AbstractArray} = a
```

please excuse me if this question is too basic.