nl_tokens: Recursively fetches all octants with the specified depth level .
pl_tokens: function findOctantsByLevel ( octant , level , depth , <mask> ) { const children = octant . children ; let i , l ; if ( depth === level ) { result . push ( octant ) ; } else if ( children !== null ) { ++ depth ; for ( i = 0 , l = children . length ; i < l ; ++ i ) { findOctantsByLevel ( children [ i ] , level , depth , result ) ; } } }