Better methods for showing metadata

I'm using metadata for the first time today (I usually use Stata and R for data cleaning) and I found it helpful to define the following functions to make it easier to see metadata

function showcolmetadata(df, col::Union{AbstractString, Symbol}, label::AbstractString)
    colmetadata(df, col, label)
end

function showcolmetadata(df, cols::AbstractVector{<:Union{AbstractString, Symbol}}, label::AbstractString)
    labvals = [colmetadata(df, col, label) for col in cols]
    nt = (; :variable => cols, Symbol(label) => labvals)
    pretty_table(nt; nosubheader = true, crop = :horizontal, alignment = [:l, :l])
end

function showcolmetadata(df, col::Union{AbstractString, Symbol}, labels::AbstractVector{<:AbstractString})
    labvals = [colmetadata(df, col, label) for label in labels]
    nt(; :label => labels, :value => labvals)
    pretty_table(nt; nosubheader = true, tile = "colmetadata for $col",  crop = :horizontal, alignment = [:l, :l])
end

function showcolmetadata(df, cols::Colon, label::AbstractString)
    showcolmetadata(df, names(df), label)
end

function showcolmetadata(df, col::Union{AbstractString, Symbol}, labels::Colon)
    d = colmetadata(df, col)
    labnames = names(d)
    showcolmetadata(df, col, labnames)
end

They would be used like following: You can see that the column names are pretty uninformative in the Penn World Tables, exactly the kind of situation metadata is great for.

julia> showcolmetadata(pwt[:, 1:10], :, "label")
┌───────────────┬──────────────────────────────────────────────────────────
│ variable      │ label                                                   ⋯
├───────────────┼──────────────────────────────────────────────────────────
│ countrycode   │ 3-letter ISO country code                               ⋯
│ country       │ Country name                                            ⋯
│ currency_unit │ Currency unit                                           ⋯
│ year          │ Year                                                    ⋯
│ rgdpe         │ Expenditure-side real GDP at chained PPPs (in mil. 2017 ⋯
│ rgdpo         │ Output-side real GDP at chained PPPs (in mil. 2017US$)  ⋯
│ pop           │ Population (in millions)                                ⋯
│ emp           │ Number of persons engaged (in millions)                 ⋯
│ avh           │ Average annual hours worked by persons engaged (source: ⋯
│ hc            │ Human capital index, see note hc                        ⋯
└───────────────┴──────────────────────────────────────────────────────────
                                                           1 column omitted

Start by reviewing the existing colmetadata API and how names(df) exposes table columns. Compare the proposed showcolmetadata overloads and their example output, then check the current tests or documentation for metadata display; done means the requested column and label combinations are supported with readable tabular output.