[pedrozath]

They're just characters. There are characters in terminal fonts introduced decades ago that allow you to draw different shapes, such as

      ⬤    ⬤  ⬤   ⬤    ⬤  ⬤   ⬤    ⬤             ⬤  ⬤
      ┍━┯━┯━┯━┯━┑    ┍━┯━┯━┯━┯━┑    ┍━┯━┯━┯━┯━┑    ┍━┯━┯━┯━┯━┑
   3  │ ⬤│ │ │ │ 8  │ │ │ │ ⬤│ 3  │ ⬤│ │ │ ⬤1  │ │ │ │ ⬤│
      ┝━┿━┿━┿━┿━┥    ┝━┿━┿━┿━┿━┥    ┝━┿━┿━┿━┿━┥    ┝━┿━┿━┿━┿━┥
   4  │ │ │ │ │ │ 9  │ │ │ │ │ │ 4  │ │ │ │ │ │ 2  │ │ ⬤│ │ │
      ┝━┿━┿━┿━┿━┥    ┝━┿━┿━┿━┿━┥    ┝━┿━┿━┿━┿━┥    ┝━┿━┿━┿━┿━┥
   5  │ │ ⬤│ ⬤│ 10 │ ⬤⬤│ │ │ 5  │ │ ⬤│ ⬤│ 3  ⬤⬤│ │ │ │
      ┝━┿━┿━┿━┿━┥    ┝━┿━┿━┿━┿━┥    ┝━┿━┿━┿━┿━┥    ┝━┿━┿━┿━┿━┥
   6  │ │ │ │ │ │ 11 │ │ │ │ │ │ 6  │ │ │ │ │ │ 4  │ │ │ │ │ │
      ┕━┷━┷━┷━┷━┙    ┕━┷━┷━┷━┷━┙    ┕━┷━┷━┷━┷━┙    ┕━┷━┷━┷━┷━┙

It doesn't align perfectly here, but on terminal it does.

[bmitc]

I thought that might be the case, but the alignment looked too good to me.