df.rolling().rank()

This is not a complete command and requires additional parameters to be specified.

However, assuming that a DataFrame is being used, `.rolling()` is a method that computes a rolling window calculation on the DataFrame. This means that a calculation is performed on a specified window of consecutive rows, which moves down the DataFrame row by row.

`.rank()` is a method that assigns a rank to each element in the DataFrame, with ties being assigned the same rank. The rank is determined by the order of the values in each column.

Therefore, `df.rolling().rank()` would perform a rolling window rank calculation on the DataFrame, although the specific parameters of the `.rolling()` method would need to be specified for this command to work.