code: def plot_line(self):
      global current_color
      self.set_color(Dark2[8][current_color])
      current_color = (current_color + 1) % len(Dark2[8])
      if self.has_bollinger_bands:
          self.set_bands_source()
          self.create_bands()
      self.line = self.plot.line(
          "index",
          self.mean_signal,
          source=self.bokeh_source,
          line_color=self.color,
          line_width=2,
      )
      # self.scatter = self.plot.scatter('index', self.mean_signal, source=self.bokeh_source)
      self.line.visible = True
  
file_path: coach/rl_coach/dashboard_components/signals.py
imports: import random
  import numpy
  from bokeh.models import ColumnDataSource
  from bokeh.palettes import Dark2
  from rl_coach.dashboard_components.globals import show_spinner, hide_spinner, current_color
  from rl_coach.utils import squeeze_list
label_desc: Use image node_id 3 for calling the Signal obj's underlying member method code with example usage: obj.plot_line() without return types