Currently ``` julia> partitions(0)|>collect 1-element Array{Any,1}: #undef ``` This is unexpected because the [partition of the empty set is the empty set](https://en.wikipedia.org/wiki/Partition_of_a_set#Examples) so I would expect ``` patitions(0)|>collect == [[]] ``` This results in unexpected behviour here: ``` julia> [length(b) for b in partitions(1)] 1-element Array{Int64,1}: 1 julia> [length(b) for b in partitions(0)] 1-element Array{Int64,1}: 4492284592 # I expect this julia> [length(b) for b in [[]]] 1-element Array{Int64,1}: 0 ```