Defining : name 'BenchmarkToools' - how?

Specific Domains Optimization (Mathematical)
10 

BenchmarkTools.Trial: 
  memory estimate:  7.94 KiB
  allocs estimate:  1
  --------------
  minimum time:     1.865 μs (0.00% GC)
  median time:      2.065 μs (0.00% GC)
  mean time:        2.892 μs (8.88% GC)
  maximum time:     227.362 μs (98.09% GC)
  --------------
  samples:          10000
  evals/sample:     10