code: def draw_custom_signals(ax, df):
      """
      Draw custom signals on the chart.
  
      """
      colors = [
          "blue",
          "green",
          "red",
          "black",
          "orange",
          "yellow",
          "pink",
      ]
  
      ax.clear()
      ax.set_title("Custom Signals")
      for index, column in enumerate(df.columns.values.tolist()):
          ax.plot(
              df.index,
              df[column],
              "-",
              color=colors[index],
              linewidth=1.0,
              label=column,
          )
  
      set_legend(ax)
      format_ax(ax)
  
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 4 for calling a global function with example usage: draw_custom_signals(ax, df) without return types