class_docstr: Observer that tracks statstics of continuous actions taken by the agent.
  
  Assumes the action is a np.ndarray, and for each dimension in the action,
  calculates some useful statistics for a particular episode.
docstr: Observes the initial state.
code: def observe_first(
      self, env: dm_env.Environment, timestep: dm_env.TimeStep
  ) -> None:
      """Observes the initial state."""
      self._actions = []
  
file_path: acme/acme/utils/observers/action_metrics.py
imports: from typing import Dict
  from acme.utils.observers import base
  import dm_env
  import numpy
label_desc: Use image node_id 2 for calling the ContinuousActionObserver obj's underlying member method code with example usage: obj.observe_first(env, timestep) without return types