Programming in Python (script).

I have 2 list (year, temperature ) with data from an input file.

Now I want to create a graph with temperature in y axis and year in x, and calculate the least square regression line.

import numpy import matplotlib.pyplot as plot

#I want to define a function and calculate the least square line and then plot it all together

def = l_s(x,y):

xn = np.linspace(???)

a, b = np.polyfit(x, y, 1) yn = np.polyval([a, b], xn)

I have trouble writting the code and plot the variables.

Any help?