class_docstr: Manage token block indexes and allocate physical memory for key and value cache
  
  Args:
      size: maximum token number used as the size of key and value buffer
      dtype: data type of cached key and value
      head_num: number of heads the memory manager is responsible for
      head_dim: embedded size per head
      layer_num: the number of layers in the model
      device: device used to store the key and value cache
docstr: free memory by updating memory states based on given indexes
code: def free(self, free_index):
      """free memory by updating memory states based on given indexes"""
      self.available_size += free_index.shape[0]
      self.mem_state[free_index] = 1
  
file_path: colossalai/colossalai/inference/kv_cache/kvcache_manager.py
imports: import torch
  from transformers.utils import logging
label_desc: Use image node_id 6 for calling the MemoryManager obj's underlying member method code with example usage: obj.free(free_index) without return types