```python
def size_list(bytes_count:       if bytes_count <        return "B"
    if bytes_count < 102        return "KB"
    return "MB"

def size_text(bytes_count):
       """ A byte count written in whole units."""
    if bytes_count < 0:
        raise ValueError("a byte count cannot be negative")
    unit = size_list(bytes_count)
       if unit == "B":
        return str(bytes_count) + " B"
    if unit == "KB"):
        return str(bytes_count // 1024) + " KB"
    return str(bytes_count // (1024 * 1024)) + " MB"
```