MIME

julia> isa(MIME("text/plain"), MIME"text/plain") # 后者生成一个类型
true

julia> show(stdout, MIME("text/plain"), [1 2;3 4])
2×2 Matrix{Int64}:
 1  2
 3  4
julia> show(stdout, MIME("text/csv"), [1 2;3 4])
1,2
3,4