> print(x)
<taxon_rank[6]>
      a       b       c       d       e       f 
[34mspecies[39m [34mspecies[39m  [90mphylum[39m  [36mfamily[39m [90mcustomA[39m [90mcustomB[39m 
Rank levels: [90mphylum[39m [90m<[39m [36mfamily[39m [90m<[39m [34mspecies[39m[90m ? [39mcustomA[90m ? [39mcustomB

