docstr: Draw a list of text labels for some bounding box on the image in upward direction.
  The next text label will be on top of the previous one.
  Args:
      text_ls (list of strings): a list of text labels.
      box_coordinate (tensor): shape (4,). The (x_left, y_top, x_right, y_bottom)
          coordinates of the box.
      y_corner (int): Value of either 1 or 3. Indicate the index of the y-coordinate of
          the box to draw labels around.
      font_size (Optional[int]): font of the text. If not provided, a font size
          proportional to the image width is calculated and used.
      color (str): color of the text. Refer to `matplotlib.colors` for full list
          of formats that are accepted.
      box_facecolors (str or list of strs): colors of the box wrapped around the text. Refer to
          `matplotlib.colors` for full list of formats that are accepted.
      alpha (float): transparency level of the box.
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code: def draw_multiple_text_upward(
      self,
      text_ls,
      box_coordinate,
      *,
      y_corner=1,
      font_size=None,
      color="w",
      box_facecolors="black",
      alpha=0.5,
  ):
      """
      Draw a list of text labels for some bounding box on the image in upward direction.
      The next text label will be on top of the previous one.
      Args:
          text_ls (list of strings): a list of text labels.
          box_coordinate (tensor): shape (4,). The (x_left, y_top, x_right, y_bottom)
              coordinates of the box.
          y_corner (int): Value of either 1 or 3. Indicate the index of the y-coordinate of
              the box to draw labels around.
          font_size (Optional[int]): font of the text. If not provided, a font size
              proportional to the image width is calculated and used.
          color (str): color of the text. Refer to `matplotlib.colors` for full list
              of formats that are accepted.
          box_facecolors (str or list of strs): colors of the box wrapped around the text. Refer to
              `matplotlib.colors` for full list of formats that are accepted.
          alpha (float): transparency level of the box.
      """
      if not isinstance(box_facecolors, list):
          box_facecolors = [box_facecolors] * len(text_ls)
      assert len(box_facecolors) == len(
          text_ls
      ), "Number of colors provided is not equal to the number of text labels."
  
      assert y_corner in [1, 3], "Y_corner must be either 1 or 3"
      if not font_size:
          font_size = self._default_font_size
  
      x, horizontal_alignment = self._align_x_coordinate(box_coordinate)
      y = box_coordinate[y_corner].item()
      for i, text in enumerate(text_ls):
          self.draw_text(
              text,
              (x, y),
              font_size=font_size,
              color=color,
              horizontal_alignment=horizontal_alignment,
              vertical_alignment="bottom",
              box_facecolor=box_facecolors[i],
              alpha=alpha,
          )
          y -= font_size + font_size // 2
  
imports: import itertools
  import logging
  import numpy
  import matplotlib.pyplot
  import torch
  from detectron2.utils.visualizer import Visualizer
  import slowfast.utils.logging
  from slowfast.utils.misc import get_class_names
label_desc: Use image node_id 4 for calling the ImgVisualizer obj's underlying member method code with example usage: obj.draw_multiple_text_upward(text_ls, box_coordinate) without return types