docs: def scatterplot_matrix(df, features, downsample_frac=None, figsize=(15, 15)):
      """
      Plot a scatterplot matrix for a list of features, colored by target value.
  
      Example: `scatterplot_matrix(X, X.columns.tolist(), downsample_frac=0.01)`
  
      Args:
          df: Pandas dataframe containing the target column (named 'target').
          features: The list of features to include in the correlation plot.
          downsample_frac: Dataframe downsampling rate (0.1 to include 10% of the dataset).
          figsize: The size of the plot.
      """
  
      if downsample_frac:
          df = df.sample(frac=downsample_frac)
  
      plt.figure(figsize=figsize)
      sns.pairplot(df[features], hue='target')
      plt.show()