I have 3 dataframes where I have one string column which I want to merge on and 2 similar columns which I want to add up
df1:
index user x y
 1    john 5 6
 2    pete 10 10 
df2:
index user x y
 1    john 1 1
 2    pete 2 2 
 3    nash 5 5
df3:
index user x y
 1    nash 6 7
 2    john 2 4 
 3    kyle 3 3
I want: df4:
index user x y
 1    john 8 11
 2    pete 12 12 
 3    nash 11 12
 4    kyle 3  3
 
    