code: def unlock(self, filename):
      if not filename in self.locks:
          # sys.stderr.write("Trying to unlock not-locked file %s.\n" % (filename))
          return True
      if self.locks[filename] == 1:
          success = safe_delete("%s.lock" % (filename))
          if not success:
              sys.stderr.write(
                  "Could not unlock file: %s.\n" % (filename)
              )
          del self.locks[filename]
          return success
      else:
          self.locks[filename] -= 1
          return True
  
file_path: auptimizer/src/aup/Proposer/spearmint/Locker.py
imports: import os
  import sys
  import time
label_desc: Use image node_id 4 for calling the Locker obj's underlying member method code with example usage: obj.unlock(filename) and returns: True, success, True