code: def tchar(tree_style, cur_level, level, item, size):
          
          if (cur_level == level):
              i1 = '1' if level == 0 else 'x'
              i2 = '1' if item  == 0 else 'x'
              i3 = 'x'
              if size == 1:
                  i3 = '1'
              elif item == (size - 1):
                  i3 = 'l'
              index = '{}{}{}'.format(i1, i2, i3)
          else:
              index = 'non' if item == (size - 1) else 'ver'
          return TREE_STYLES[tree_style][index]
docs: Retrieve tree character for particular tree node.