code: def format_ax(ax):
      """
      Trying to assign reasonable parameters to the time axis.
  
      Parameters
      ----------
      ax:
  
      """
      # TODO: room for improvement
      ax.xaxis.set_major_locator(mdates.DayLocator(interval=1))
      ax.xaxis.set_major_formatter(fmt)
  
      locator = mdates.HourLocator(interval=4)
      locator.MAXTICKS = 5000
      ax.xaxis.set_minor_locator(locator)
  
      datemin = pd.Timestamp.utcnow()
      ax.set_xlim(datemin)
  
      ax.grid(True)
  
file_path: catalyst/catalyst/exchange/utils/live_chart_utils.py
imports: import matplotlib.dates
  import pandas
  from catalyst.exchange.exchange_errors import MismatchingQuoteCurrenciesExchanges
label_desc: Use image node_id 1 for calling a global function with example usage: format_ax(ax) without return types