# length: interfaces.jl
# endof: interfaces.jl
# size: interfaces.jl
# getindex: interfaces.jl
# start: interfaces.jl
# done: interfaces.jl
# next: interfaces.jl
# indexed_next: Not exported
# eltype: interfaces.jl
# ntuple
# map
# heads: Not exported
# tails: Not exported
# isequal: interfaces.jl
# ==: interfaces.jl
# hash: works for Node
# isless: interfaces.jl
# isempty: interfaces.jl
# revargs: Not exported
# reverse
# sum
# prod
# all
# any
