code: def merge(self, prev_size: int = 0):
      from_step = max(0, prev_size - 1)
      if len(self) - from_step <= 1:
          return
  
      if from_step > 0:
          prev_last_step = self.last_step[from_step - 1].item()
      else:
          prev_last_step = 0
  
      n = self._merge(
          self.value,
          self.last_step,
          self.step,
          prev_last_step,
          from_step,
      )
  
      self.last_step = self.last_step[:n]
      self.step = self.step[:n]
      self.value = self.value[:n]
  
imports: import math
  from typing import Dict, List, Optional, Union
  from datetime import datetime, timedelta
  import numpy
label_desc: Use image node_id 12 for calling the Series obj's underlying member method code with example usage: obj.merge(prev_size) without return types