```python
from typing import List

def split_at(entries: List[str], marker: str) -> List[str]:
    """
    Break a list in two at the first entry equal to a marker, returning what stood before it and what stood after, with the marker itself in neither.
    A list not holding the marker gives everything as the first part and nothing as the second.
    """
    if marker not in entries:
        return entries, []
    index = entries.index(marker)
    return entries[:index], entries[index + 1:]
```