code: def update_range(self):
      self.min_val = np.min(self.bokeh_source.data[self.mean_signal])
      self.max_val = np.max(self.bokeh_source.data[self.mean_signal])
  
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 9 for calling the Signal obj's underlying member method code with example usage: obj.update_range() without return types