class_docstr: A high level game controller class for maze levels.
  
  The class allows navigating DMLab mazes using high level actions.
class_docstr_tok: ["A","high","level","game","controller","class","for","maze","levels",".","The","class","allows","navigating","DMLab","mazes","using","high","level","actions","."]
docstr: Return locations of all pickups in the current maze.
docstr_tok: ["Return","locations","of","all","pickups","in","the","current","maze","."]
code: def _find_pickup_locations(self):
      """Return locations of all pickups in the current maze."""
      if self._pickup_locations is None:
          maze_str = self._env.observations()[
              "DEBUG.MAZE.LAYOUT"
          ].strip()
          lines = maze_str.split("\n")
  
          self._pickup_locations = []
          for j, line in enumerate(lines):
              for i, cell in enumerate(line):
                  if cell == _PICKUP_SYMBOL:
                      self._pickup_locations.append((i, j))
      return self._pickup_locations
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  from python.tests.utils import game_controller
label_desc: Use image node_id 11 for calling the MazeGameController obj's underlying member method code with example usage: obj._find_pickup_locations() and returns: self