# T \<: T question
**URL:** https://discourse.julialang.org/t/t-t-question/3449
**Category:** General Usage
**Tags:** question, documentation
**Created:** [May 1, 2017, 1:50am UTC](https://discourse.julialang.org/t/t-t-question/3449 "2017-05-01T01:50:17Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)
#### Post date: [May 1, 2017, 1:50am UTC](https://discourse.julialang.org/t/t-t-question/3449/1 "2017-05-01T01:50:17Z")
Does the example below from Types chapter of Julia manual depend on `Real <: Real` being true? I’m assuming that author’s intention was to include the first definition of `norm` in more generic definition, which follows.
> Since Point{Float64} is not a subtype of Point{Real}, the following method can’t be applied to arguments of type Point{Float64}:
> ```
> function norm(p::Point{Real})
> sqrt(p.x^2 + p.y^2)
> end
>
> ```
> The correct way to define a method that accepts all arguments of type Point{T} where T is a subtype of Real is:
> ```
> function norm{T<:Real}(p::Point{T})
> sqrt(p.x^2 + p.y^2)
> end
>
> ```
---
### Author:  [@yuyichao](https://discourse.julialang.org/u/yuyichao)
#### Post date: [May 1, 2017, 4:14am UTC](https://discourse.julialang.org/t/t-t-question/3449/2 "2017-05-01T04:14:27Z")
> [@pauljurczak](#):
>
> Does the example below from Types chapter of Julia manual depend on Real \<: Real being true? I’m assuming that author’s intention was to include the first definition of norm in more generic definition, which follows.
What depend on that? It does “depend” on that being true so that the second signature is a strict superset of the first one though it’s a little weird since `T<:T` being true is a fundamental property of the type system that’s much more important than handling this special case that isn’t very important…
---
### Author:  [@pauljurczak](https://discourse.julialang.org/u/pauljurczak)
#### Post date: [May 1, 2017, 5:12am UTC](https://discourse.julialang.org/t/t-t-question/3449/3 "2017-05-01T05:12:17Z")
> [@yuyichao](#):
>
> second signature is a strict superset of the first one
That’s what I wanted to know. By _depend_ I meant the narrative and the line of reasoning in that paragraph of Julia’s manual. It wasn’t clear to me as I’m just beginning with Julia. I should have worded my question more precisely.