You've got a dataset from a music shop. It contains information on customers, ukuleles, and guitars sold each month during a year. Here's what it looks like:
+----+---------+-------------+------------+-----------+
| | month | customers | ukuleles | guitars |
|----+---------+-------------+------------+-----------|
| 0 | 1 | 252 | 30 | NaN |
| 1 | 2 | 311 | 32 | 17 |
| 2 | 3 | 304 | 34 | 19 |
| 3 | 4 | 290 | 30 | Nan |
| 4 | 5 | 317 | 39 | 20 |
+----+---------+-------------+------------+-----------+
However, there are some NaN values. Before you plot the data, you need to preprocess it: remove all the NaN rows and get rid of the month column (since we won't need it for further analysis, be it univariate or bivariate distribution). Do it and print the resulting dataset.