text: import numpy as np
  import matplotlib.pyplot as plt
  
  
  from sal_timer import timer
  
  
  
  def plot_1():
      # ...
      ax = plt.subplot(111)
  
      t = np.arange(0.0, 5.0, 0.01)
      s = np.cos(2*np.pi*t)
      line, = plt.plot(t, s, lw=2)
  
      # ...
      plt.text(1, -1.5, r'$\mu=100,\ \sigma=15$')
      plt.text(4, 1.5, r'$\sum_{i=0}^\infty x_i$')
      
      plt.annotate(
          'local max',
          xy=(2, 1),
          xytext=(3, 1.5),
          arrowprops=dict(facecolor='black', shrink=0.05),
          )
  
      plt.ylim(-2, 2)
      plt.show()
  
  
  
  
  
  
  @timer
  def main():
      # https://matplotlib.org/tutorials/text/mathtext.html
      # https://matplotlib.org/tutorials/text/text_props.html
      plot_1()
  
  
  if __name__ == '__main__':
      print('========================================== START ==========================================')
      #...
      main()
      print('========================================== END ============================================')