docstr: Calculates estimated time left until completion.
docstr_tok: ["Calculates","estimated","time","left","until","completion","."]
code: def _calc_eta(self):
      """Calculates estimated time left until completion."""
      elapsed = self._elapsed()
      if self.cnt == 0 or elapsed < 0.001:
          return None
      rate = float(self.cnt) / elapsed
      self.eta = (float(self.max_iter) - float(self.cnt)) / rate
  
imports: import os
  import sys
  import time
  from io import UnsupportedOperation
label_desc: Use image node_id 6 for calling the Prog obj's underlying member method code with example usage: obj._calc_eta() and returns: None