in src/metadata/Schema.jl [519:542]
function Type(::Base.Type{T})::Int16 where {T}
T == Null && return 1
T == Int && return 2
T == FloatingPoint && return 3
T == Binary && return 4
T == Utf8 && return 5
T == Bool && return 6
T == Decimal && return 7
T == Date && return 8
T == Time && return 9
T == Timestamp && return 10
T == Interval && return 11
T == List && return 12
T == Struct && return 13
T == Union && return 14
T == FixedSizeBinary && return 15
T == FixedSizeList && return 16
T == Map && return 17
T == Duration && return 18
T == LargeBinary && return 19
T == LargeUtf8 && return 20
T == LargeList && return 21
return 0
end