class_docstr: Timer.
class_docstr_tok: ["Timer","."]
docstr: Start the timer.
docstr_tok: ["Start","the","timer","."]
code: def start(self):
      """Start the timer."""
      assert (
          not self.started_
      ), f"{self.name_} timer has already been started"
      self.start_time = time.time()
      self.started_ = True
  
imports: import time
  from .callback import Callback
  from ..log import logger
label_desc: Use image node_id 2 for calling the _Timer obj's underlying member method code with example usage: obj.start() without return types