docs: def binarize(qualitative):
      """
      binarizes an expression dataset.
      """
      thresholds = qualitative.min(1) + (qualitative.max(1) - qualitative.min(1))/2.0
      binarized = qualitative > thresholds.reshape((len(thresholds), 1)).repeat(8,1)
      return binarized.astype(int)