Plot linegraph in matplotlib with row data as legends

date    col1 col2 
Jan-99  A   1
Jan-99  B   2
Feb-99  A   3
Feb-99  B   4
Mar-99  A   212
Mar-99  B   343

I have a dataframe like this. I need to plot a linegraph. But I need two lines in this graph one for each type of col1. One line plotting values in col2 for A another line plotting values in col2 for B. And a legend should be there denoting the color for A&B. Below is the code used to plot just a normal line graph. How should i specify legends here and the legends being A&B

fig = plt.figure(figsize=(90,70)) 
ax = fig.add_subplot(1, 1, 1)
ax.tick_params(direction='out', length=10, width=3,labelsize=35)
df1.plot(ax=ax,x='date',y=['col1'],linewidth=7.0)
ax.set_xlabel("date",size=40)
ax.set_ylabel("value",size=40)
plt.legend(df1['col1'])
ax.set_title("graph",size=50)

This legend specification is not working and is giving me just one line and not two lines. I see some examples where people draw multiple plots and combine them. I dont want to do that and want to use this one dataframe and specify legends as the values stored in col1. Is this possible?