'x' set_hist_ 9
9
   'x' set_hist_ 10
10
   'x' set_hist_ 11
11
   get_hist_ 'x'
11
   length_hist_ 'x'
3
   getall_hist_ 'x'
┌─┬──┬──┐
│9│10│11│
└─┴──┴──┘