message: Elaborate doc string
diff: @@ -355,7 +355,7 @@ class BettiCurve(BaseEstimator, TransformerMixin):
  class BettiCurve2(BaseEstimator, TransformerMixin):
  """
  - A more flexible replacement for the BettiCurve class.
  + A more flexible replacement for the BettiCurve class. There are two modes of operation: with a predefined grid, and without. With a predefined grid, the class computes the Betti numbers at those grid points. Without a predefined grid, it can be fit to a list of persistence diagrams and produce a grid that consists of (at least) the filtration values at which at least one of those persistence diagrams chance Betti numbers, and then compute the Betti numbers at those grid points. In the latter mode, the exact Betti curve is computed for the entire real line.
  Parameters
  ----------
  