auto randomSample(Range)(Range r, size_t n, size_t total) if (isInputRange!Range)
Ditto
auto randomSample(Range)(Range r, size_t n) if (isInputRange!Range && hasLength!Range)
auto randomSample(Range, UniformRNG)(Range r, size_t n, size_t total, auto ref UniformRNG rng) if (isInputRange!Range && isUniformRNG!UniformRNG)
auto randomSample(Range, UniformRNG)(Range r, size_t n, auto ref UniformRNG rng) if (isInputRange!Range && hasLength!Range && isUniformRNG!UniformRNG)