message: Rewrite python doc
diff: @@ -621,12 +621,14 @@ cdef class SimplexTree:
  return (normal0, normals, infinite0, infinites)
  def collapse_edges(self, nb_iterations = 1):
  - """Assuming the simplex tree is a 1-skeleton graph, this method collapse edges (simplices of higher dimension
  - are ignored) and resets the simplex tree from the remaining edges.
  - A good candidate is to build a simplex tree on top of a :class:`~gudhi.RipsComplex` of dimension 1 before
  - collapsing edges
  + """Assuming the complex is a graph (simplices of higher dimension are ignored), this method implicitly
  + interprets it as the 1-skeleton of a flag complex, and replaces it with another (smaller) graph whose
  + expansion has the same persistent homology, using a technique known as edge collapses
  + (see :cite:`edgecollapsearxiv`).
  +
  + A natural application is to get a simplex tree of dimension 1 from :class:`~gudhi.RipsComplex`,
  + then collapse edges, perform :meth:`expansion()` and finally compute persistence
  (cf. :download:`rips_complex_edge_collapse_example.py <../example/rips_complex_edge_collapse_example.py>`).
  - For implementation details, please refer to :cite:`edgecollapsesocg2020`.
  :param nb_iterations: The number of edge collapse iterations to perform. Default is 1.
  :type nb_iterations: int
  