有人回答吗？感谢啊

import numpy as np
from matplotlib import pylab
import seaborn as sns
font.set_size(20)
x = np.linspace(1.0, 13.0, 7)
y = np.sin(x)
pylab.figure(figsize = (12,6))
pylab.scatter(x,y, s = 85, marker='x', color = 'r')
pylab.title(u'$f(x)$离散点分布', fontproperties = font)


（python3.7）

运行结果：Traceback (most recent call last):
     File "D:\python\learn\绘制散点图.py", line 4, in <module>
    font.set_size(20)
    NameError: name 'font' is not defined