code: def histogram_plot(value: List[np.ndarray], **kwargs) -> None:
      """Plots histograms of all observations (default behaviour).
  
      :param value: A list of observation arrays.
      :param kwargs: Additional plotting relevant arguments.
      """
      unused(kwargs)
  
      flat_values = np.stack(value).flatten()
  
      fig = plt.figure(figsize=(7, 5))
      plt.hist(flat_values)
      return fig
  
imports: from abc import ABC
  import warnings
  from typing import TypeVar, Union, Any, Tuple, Dict, Optional, List, Callable
  import matplotlib.pyplot
  import numpy
  from maze.core.annotations import override, unused
  from maze.core.env.action_conversion import ActionType
  from maze.core.env.base_env import BaseEnv
  from maze.core.env.maze_action import MazeActionType
  from maze.core.env.maze_env import MazeEnv
  from maze.core.env.maze_state import MazeStateType
  from maze.core.env.observation_conversion import ObservationType
  from maze.core.env.simulated_env_mixin import SimulatedEnvMixin
  from maze.core.env.structured_env import StructuredEnv
  from maze.core.log_stats.event_decorators import define_plot, define_epoch_stats, define_episode_stats, define_step_stats, define_stats_grouping
  from maze.core.log_stats.reducer_functions import histogram
  from maze.core.utils.factory import Factory
  from maze.core.wrappers.wrapper import Wrapper
label_desc: Use image node_id 1 for calling a global function with example usage: histogram_plot(value) and returns: fig