readme: This directory includes a few sample datasets to get you started.
  
  *   `california_housing_data*.csv` is California housing data from the 1990 US
      Census; more information is available at:
      https://developers.google.com/machine-learning/crash-course/california-housing-data-description
  
  *   `mnist_*.csv` is a small sample of the
      [MNIST database](https://en.wikipedia.org/wiki/MNIST_database), which is
      described at: http://yann.lecun.com/exdb/mnist/
  
  *   `anscombe.json` contains a copy of
      [Anscombe's quartet](https://en.wikipedia.org/wiki/Anscombe%27s_quartet); it
      was originally described in
  
      Anscombe, F. J. (1973). 'Graphs in Statistical Analysis'. American
      Statistician. 27 (1): 17-21. JSTOR 2682899.
  
      and our copy was prepared by the
      [vega_datasets library](https://github.com/altair-viz/vega_datasets/blob/4f67bdaad10f45e3549984e17e1b3088c731503d/vega_datasets/_data/anscombe.json).
  