old_contents: from .address import Address
  
  from typing import Dict
  
  
  Environment = Dict[str, Address]
  
  
  def empty_env() -> Environment:
      return Environment()
  
  
  def extend_env(env: Environment, name: str, value: Address) -> Environment:
      new_env = env.copy()
      new_env[name] = value
      return new_env
  
new_contents: from .address import Address
  
  from typing import Dict
  
  
  Environment = Dict[str, Address]
  
  
  def empty_env() -> Environment:
      return dict()
  
  
  def extend_env(env: Environment, name: str, value: Address) -> Environment:
      new_env = env.copy()
      new_env[name] = value
      return new_env
  
subject: Revise Environment instatiation