What does the `cor` in `dt_line_cor` stand for?

[GalacticStarfish]

What does the abbreviation cor in variable named dt_line_cor represent?

This is in the method tree.__get_iter

dt_vline, dt_box, dt_line_cor = dt

clearly vline is "vertical line," but I'm not sure what cor is supposed to signify.

[GalacticStarfish]

I figured it out. "cor" stands for "corner." I really wish someone would write some documentation for the code.