code: def plot_hs(fignum, Ys, c, ls):
      
      fig = plt.figure(num=fignum)
      for yv in Ys:
          bounds = plt.axis()
          plt.axhline(y=yv, xmin=0, xmax=1, linewidth=1, color=c, linestyle=ls)
docs: plots  horizontal lines at Ys values
  
      Parameters
      _________
      fignum : matplotlib figure number
      Ys : list of Y values for lines
      c : color for lines
      ls : linestyle for lines