code: def overplot_ds9reg(filename, ax):
      
  
      # read ds9 region file
      with open(filename) as f:
          file_content = f.read().splitlines()
  
      # check first line
      first_line = file_content[0]
      if "# Region file format: DS9" not in first_line:
          raise ValueError("Unrecognized ds9 region file format")
  
      for line in file_content:
          if line[0:4] == "line":
              line_fields = line.split()
              x1 = float(line_fields[1])
              y1 = float(line_fields[2])
              x2 = float(line_fields[3])
              y2 = float(line_fields[4])
              if "color" in line:
                  i = line.find("color=")
                  color = line[i+6:i+13]
              else:
                  color = "green"
              ax.plot([x1,x2], [y1,y2], '-', color=color)
          elif line[0:4] == "text":
              line_fields = line.split()
              x0 = float(line_fields[1])
              y0 = float(line_fields[2])
              text=line_fields[3][1:-1]
              if "color" in line:
                  i = line.find("color=")
                  color = line[i+6:i+13]
              else:
                  color = "green"
              ax.text(x0, y0, text, fontsize=8,
                      bbox=dict(boxstyle="round,pad=0.1", fc="white", ec="grey", ),
                      color=color, fontweight='bold', backgroundcolor='white',
                      ha='center')
          else:
              # ignore
              pass
docs: Overplot a ds9 region file.
  
      Parameters
      ----------
      filename : str
          File name of the ds9 region file.
      ax : matplotlib axes instance
          Matplotlib axes instance.