class_docstr: Cumulatively sums the values in the stream.
  
  Introduced in: https://arxiv.org/pdf/1603.03788.pdf
  
  Parameters
  ----------
  append_zero: bool
      Set True to append zero to the path before taking the cumulative sum.
class_docstr_tok: ["Cumulatively","sums","the","values","in","the","stream",".","Introduced","in",":","https",":","\/\/arxiv.org\/pdf\/1603.03788.pdf","Parameters","--","--","--","--","--","append_zero",":","bool","Set","True","to","append","zero","to","the","path","before","taking","the","cumulative","sum","."]
code: def _transform(self, X, y=None):
      if self.append_zero:
          X = _BasePoint().fit_transform(X)
      Xt = np.cumsum(X, 2)
      return Xt
  
imports: import numpy
  from sklearn.pipeline import Pipeline
  from sktime.transformations.base import BaseTransformer
label_desc: Use image node_id 2 for calling the _CumulativeSum obj's underlying member method code with example usage: obj._transform(X, y) and returns: Xt