code: def flush(self):
          
          garbage = []
          for i, (x, signature) in self.refs.items():
              if sys.getrefcount(x) == 3:
                  garbage.append(i)
  
              if fingerprint(x) == signature: continue
  
              self.filehandle.puttr(i, x)
              signature = fingerprint(x)
  
  
          # to avoid too many resource leaks, when this dict is the only one
          # holding references to already-produced traces, clear them
          for i in garbage:
              del self.refs[i]
docs: Commit cached writes to the file handle. Does not flush libc buffers or
          notifies the kernel, so these changes may not immediately be visible to
          other processes.
  
          Updates the fingerprints whena writes happen, so successive ``flush()``
          invocations are no-ops.
  
          It is not necessary to call this method in user code.
  
          Notes
          -----
          .. versionadded:: 1.6
  
          This method is not intended as user-oriented functionality, but might
          be useful in certain contexts to provide stronger guarantees.