# Display Error: Error: method not implemented

**URL:** <https://discourse.julialang.org/t/display-error-error-method-not-implemented/81050>\
**Category:** New to Julia\
**Tags:** flux\
**Created:** [May 14, 2022, 8:17am UTC](https://discourse.julialang.org/t/display-error-error-method-not-implemented/81050 "2022-05-14T08:17:15Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![imantha](https://avatars.discourse-cdn.com/v4/letter/i/6a8cbe/32.png) [@imantha](https://discourse.julialang.org/u/imantha)\
**Post date:** [May 14, 2022, 8:17am UTC](https://discourse.julialang.org/t/display-error-error-method-not-implemented/81050/1 "2022-05-14T08:17:15Z")

</div>

Hi

I am following a turotrial from here [⚡ Pluto.jl ⚡](https://juliareinforcementlearning.org/ReinforcementLearningAnIntroduction.jl/notebooks/Chapter05_Blackjack.html)

when I construct a struct and try to instantiate it I get the following error. `Display Error: ERROR: method not implemented` Any idea what the issue is?

```julia
using ReingorcementLearning: AbstractEnv

mutable struct BlackjackEnv <: AbstractEnv
    dealer_hand::Vector{Int}
    player_hand::Vector{Int}
    done::Bool
    reward::Int 
    init::Union{Tuple{Vector{Int}, Vector{Int}}, Nothing}
end

BlackjackEnv([],[],false, 0, nothing)

>>> Display Error: ERROR: method not implemented

```