code: def _get_symbol_by_slope(
          self,
          slope,
          default_symbol
          ):
  
          
  
          if slope > math.tan(3 * math.pi / 8):
              draw_symbol = "|"
          elif math.tan(math.pi / 8) < slope < math.tan(3 * math.pi / 8):
              draw_symbol = u"\u27cb" # "/"
          elif abs(slope) < math.tan(math.pi / 8):
              draw_symbol = "-"
          elif slope < math.tan(-math.pi / 8) and\
              slope > math.tan(-3 * math.pi / 8):
              draw_symbol = u"\u27CD" # "\\"
          elif slope < math.tan(-3 * math.pi / 8):
              draw_symbol = "|"
          else:
              draw_symbol = default_symbol
          return draw_symbol
docs: return line oriented approximatively along the slope value