class_docstr: A window of fixed length, slid along the dataset.
docstr: Build a Expanding object.
  
  Parameters
  ----------
  length: int, The length of each window.
  step: int, The step size.
docstr_tok: ["Build","a","Expanding","object",".","Parameters","--","--","--","--","--","length",":","int",",","The","length","of","each","window",".","step",":","int",",","The","step","size","."]
code: def __init__(self, length, step):
      """Build a Expanding object.
  
      Parameters
      ----------
      length: int, The length of each window.
      step: int, The step size.
      """
      super().__init__(
          initial_length=length, start_step=0, end_step=step
      )
  
imports: import collections
  import numpy
label_desc: Use image node_id 1 to create a new _Expanding object from inherited base classes: _ExpandingSliding with example: obj = _Expanding(length, step)