class_docstr: Preallocation strategies for rolling window over expanding data set
  
  Restrictions: major_axis can only be a DatetimeIndex for now
class_docstr_tok: ["Preallocation","strategies","for","rolling","window","over","expanding","data","set","Restrictions",":","major_axis","can","only","be","a","DatetimeIndex","for","now"]
docstr: Get the oldest frame in the panel.
docstr_tok: ["Get","the","oldest","frame","in","the","panel","."]
code: def oldest_frame(self, raw=False):
      """
      Get the oldest frame in the panel.
      """
      if raw:
          return self.buffer.values[:, self._start_index, :]
      return self.buffer.iloc[:, self._start_index, :]
  
imports: import datetime
  from copy import deepcopy
  import numpy
  import pandas
label_desc: Use image node_id 5 for calling the RollingPanel obj's underlying member method code with example usage: obj.oldest_frame(raw) and returns: self, self