graph from dataframe columns where the curve change its color if date is grater than X

def graph_color(df, date, date_col, x, y):
  fig, ax = plt.subplots(figsize=(10,5))
  up_date = df.loc[df[date_col] <= date]
  down_date = df.loc[df[date_col] > date]
  ax.plot(up_date[x], up_date[y], '--')
  ax.plot(down_date[x], down_date[y], '--')
  ax.set_title('My Graph')
  ax.set_ylabel('y_label')
  ax.set_xlabel('x_label')
  ax.legend(['Before', 'After'])
  plt.show()

graph_color(df, '2020-04-01', 'date', 'date', 'col_name')