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      |
    +------------------------+---------------------------------+

def setup_main_filler(name: str, environment: Dict[Any, Any]=None) -> Dict[str, Dict[str, Any]]:
    """
    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      |
    +------------------------+---------------------------------+
    """
    return setup_filler(name, merge(DEFAULT_MAIN_ENVIRONMENT, environment or {}))