code: def setup_main_filler(name: str, environment: Dict[Any, Any]=None) -> Dict[str, Dict[str, Any]]:
      
      return setup_filler(name, merge(DEFAULT_MAIN_ENVIRONMENT, environment or {}))
docs: Kick off the filler generation process by creating the general filler scaffold with
      a test name and general information about the testing environment.
  
      For tests for the main chain, the `environment` parameter is expected to be a dictionary with
      some or all of the following keys:
  
      +------------------------+---------------------------------+
      | key                    | description                     |
      +========================+=================================+
      | ``"currentCoinbase"``  | the coinbase address            |
      +------------------------+---------------------------------+
      | ``"currentNumber"``    | the block number                |
      +------------------------+---------------------------------+
      | ``"previousHash"``     | the hash of the parent block    |
      +------------------------+---------------------------------+
      | ``"currentDifficulty"``| the block's difficulty          |
      +------------------------+---------------------------------+
      | ``"currentGasLimit"``  | the block's gas limit           |
      +------------------------+---------------------------------+
      | ``"currentTimestamp"`` | the timestamp of the block      |
      +------------------------+---------------------------------+