class_docstr: Cut Operator
  
  Parameters
  ----------
  feature : Expression
      feature instance
  l : int
      l > 0, delete the first l elements of feature (default is None, which means 0)
  r : int
      r < 0, delete the last -r elements of feature (default is None, which means 0)
  Returns
  ----------
  feature:
      A series with the first l and last -r elements deleted from the feature.
      Note: It is deleted from the raw data, not the sliced data
class_docstr_tok: ["Cut","Operator","Parameters","--","--","--","--","--","feature",":","Expression","feature","instance","l",":","int","l",">","0",",","delete","the","first","l","elements","of","feature","(","default","is","None",",","which","means","0",")","r",":","int","r","<","0",",","delete","the","last","-r","elements","of","feature","(","default","is","None",",","which","means","0",")","Returns","--","--","--","--","--","feature",":","A","series","with","the","first","l","and","last","-r","elements","deleted","from","the","feature",".","Note",":","It","is","deleted","from","the","raw","data",",","not","the","sliced","data"]
code: def _load_internal(self, instrument, start_index, end_index, freq):
      series = self.feature.load(
          instrument, start_index, end_index, freq
      )
      return series.iloc[self.left : self.right]
  
imports: import numpy
  import pandas
  from datetime import datetime
  from qlib.data.cache import H
  from qlib.data.data import Cal
  from qlib.data.ops import ElemOperator, PairOperator
  from qlib.utils.time import time_to_day_index
label_desc: Use image node_id 2 for calling the Cut obj's underlying member method code with example usage: obj._load_internal(instrument, start_index, end_index, freq) and returns: series