class_docstr: 1-dimensional grid-world implementation with 3 possible movement actions ("LEFT", "STAY", "RIGHT")
code: def step(self, action):
      state = self.P[self.state][action]
      self.state = state
      self.last_action = action
      return state
  
imports: import numpy
  import matplotlib.pyplot
  import seaborn
  from pymdp.envs import Env
label_desc: Use image node_id 4 for calling the DGridWorldEnv obj's underlying member method code with example usage: obj.step(action) and returns: state