title: How to add Threads to ParallelAccelerator.jl in julia?
body: <p>I was reading the documentations.But I never fond "<strong>By which command I can add threads for ParallelAccelerator.jl</strong>?"
  is that <code>export JULIA_NUM_THREADS=4</code>
  or <code>export OMP_NUM_THREADS=4</code>?
  And how can I get number of threads in the code? am I able to get number of threads by <code>Threads.nthread()</code> in the code?
  Thank you.</p>