```python
def fresh_value(entry: dict, now:       if not isinstance(entry, dict:
        raise ValueError("entry must be a dictionary")
    
    if 'value' not in entry or not isinstance(entry['value'], str):
        raise ValueError("entry must contain a 'value' field that is a string")
    
          if 'stored'not in entry or not isinstance(entry['stored'], int) or entry['stored'] <        raise ValueError("entry must contain a 'stored' field that is a non")
    
             if 'ttl' not in entry or not isinstance(entry['ttl'], int) or entry['ttl']:
        raise ValueError("entry must contain a 'ttl' field that is a positive integer")
    
    if 'fresh' not in entry or not isinstance(entry['fresh'], int) or entry['fresh'] < entry['stored']:
        raise ValueError("entry must contain a 'fresh' field that is an integer at least 'stored'")
    
    if entry['fresh'] >= entry['stored'] + entry['ttl']:
        raise ValueError("record is no longer usable at now")
    
    return entry['value']
```