christophfeinauer

import Base: start, next, done, eltype, length, size
immutable SelfPairs
        xs
        n::Int
end

eltype(it::SelfPairs) = eltype(it.xs)

length(it::SelfPairs) = binomial(it.n,2)

christophfeinauer

import Base: GLOBAL_RNG, rand, isslotfilled
function rand(rng::AbstractRNG, d::Dict)
        isempty(d) && throw(ArugmentError("dictionary must be non-empty"))
        n = length(d.keys)
        while true
                i = rand(rng,1:n)
                !isdefined(d.keys,i) && continue
                return d.keys[i],d.vals[i]
        end
end