How I can iterate over columns with index in pandas, for rows we can use `for i, j in df.iterrows():` which will give the index and the row.

Is there anything similar for columns? 

```
spice smice skice bike dike mike 
    1     23     35    34   34   56 
    135   34     23    21   56   34
    231   12     67    21   62   75

```

I am trying to use a nested for loop like the following:

```
for index, col1 in  df.columns:
  for col2 in df.columns[index:]:

```

Is there any better way of doing this?