old_contents: import os
  import xgboost as xgb
  
  ### simple example for using external memory version
  
  # this is the only difference, add a # followed by a cache prefix name
  # several cache file with the prefix will be generated
  # currently only support convert from libsvm file
  CURRENT_DIR = os.path.dirname(__file__)
  dtrain = xgb.DMatrix(os.path.join(CURRENT_DIR, '../data/agaricus.txt.train'))
  dtest = xgb.DMatrix(os.path.join(CURRENT_DIR, '../data/agaricus.txt.test'))
  
  # specify validations set to watch performance
  param = {'max_depth':2, 'eta':1, 'objective':'binary:logistic'}
  
  # performance notice: set nthread to be the number of your real cpu
  # some cpu offer two threads per core, for example, a 4 core cpu with 8 threads, in such case set nthread=4
  #param['nthread']=num_real_cpu
  
  watchlist = [(dtest, 'eval'), (dtrain, 'train')]
  num_round = 2
  bst = xgb.train(param, dtrain, num_round, watchlist)
  
new_contents: import os
  import xgboost as xgb
  
  ### simple example for using external memory version
  
  # this is the only difference, add a # followed by a cache prefix name
  # several cache file with the prefix will be generated
  # currently only support convert from libsvm file
  CURRENT_DIR = os.path.dirname(__file__)
  dtrain = xgb.DMatrix(os.path.join(CURRENT_DIR, '../data/agaricus.txt.train#dtrain.cache'))
  dtest = xgb.DMatrix(os.path.join(CURRENT_DIR, '../data/agaricus.txt.test#dtest.cache'))
  
  # specify validations set to watch performance
  param = {'max_depth':2, 'eta':1, 'objective':'binary:logistic'}
  
  # performance notice: set nthread to be the number of your real cpu
  # some cpu offer two threads per core, for example, a 4 core cpu with 8 threads, in such case set nthread=4
  #param['nthread']=num_real_cpu
  
  watchlist = [(dtest, 'eval'), (dtrain, 'train')]
  num_round = 2
  bst = xgb.train(param, dtrain, num_round, watchlist)
  
subject: Add cache name back to external_memory.py files. (#6088)