I'm trying to make a function that adds new columns with numbering:

```
x = [i+1 for i in range(len(df))]

def new_column (df, column):
  df.sort_values(by=column, ascending=False)
  df['new_col'] = x

```

But, when I call it, I get an eroor:

```
new_column(df, column_name)

```

> 
> NameError: name 'column' is not defined
> 
> 
> 

What did I do wrong?