I have a DataFrame like that:
index A B C
0     1 0 2
1     0 0 3
2     0 1 5
3     0 2 1
4     1 2 2
5     0 2 5
And I need to get only the rows that contains number 1, but the number 1 can be in any column in df.
Ex:
index A B C
0     1 0 2
2     0 1 5
3     0 2 1
4     1 2 2