Example
using PopSimIBX
using StatsBase
pop = StationaryPopulation(;
    popoulation_size = 1000,
    genome_length = 100_000_000, 
    mutation_rate = 1e-7, recombination_rate = 1e-7)
hist = Histogram(1:1000:1_000_001)
append!(hist, IBSIterator(SMCprime.IBDIterator(pop), pop.mutation_rate))using PopSimIBX
using StatsBase
Ts = [0, 200, 400]
Ns = [1_000, 100, 1_000]
pop = VaryingPopulation(;
    genome_length = 100_000_000, 
    mutation_rate = 1e-7, recombination_rate = 1e-7,
    population_sizes = Ns,
    times = Ts
    )
hist = Histogram(1:1000:1_000_001)
append!(hist, IBSIterator(SMCprime.IBDIterator(pop), pop.mutation_rate))