from typing import List


def FlattenList(L:List):
    """Flatten an embedded list to a 1D list.

    Args:
        L: The embedded list to be flattened.
    Returns:
        List: The flattened list.
    """
    F = lambda x:[e for i in x for e in F(i)] if isinstance(x,list) else [x]; return F(L)