Benchmark: timing 100000 iterations of dotstar, first_n_last_1, first_n_last_2...
   dotstar:  7 wallclock secs ( 6.91 usr +  0.02 sys =  6.93 CPU) @ 14430.01/s (n=100000)
first_n_last_1:  4 wallclock secs ( 4.21 usr +  0.00 sys =  4.21 CPU) @ 23775.56/s (n=100000)
first_n_last_2:  2 wallclock secs ( 1.30 usr +  0.00 sys =  1.30 CPU) @ 76804.92/s (n=100000)