想像以上にアホの子かもな

julia> "あいう"[end:end]
"う"
julia> "あいう"[end-1:end]
ERROR: UnicodeError: invalid character index
julia> "あいう"[end-3:end]
"いう"
julia> "あいう"[1:end]
"あいう"
julia> "あいう"[2:end]
ERROR: UnicodeError: invalid character index
julia> "あいう"[2]
ERROR: UnicodeError: invalid character index
julia> "あいう"[3]
ERROR: UnicodeError: invalid character index
julia> "あいう"[4]
'い'
julia> length("あいう")
3
julia> length("1いう")
3
julia> ("1いう")[2]
'い'
julia> ("1いう")[end]
'う'
julia> ("1いう")[3]
ERROR: UnicodeError: invalid character index