"""Create fact_checker
Generated by Phi-Octopus Eden
2025-11-08 03:08:20.551945
"""

```python
from typing import List, Optional
from datetime import datetime, timedelta

class FactChecker:
    """
    A class that checks the validity of facts based on a predefined set of rules.
    
    Attributes:
        fact_history (List[str]): A list to keep track of checked facts for history purposes.
        current_date (datetime): The date against which facts are being validated.
    """
    
    def __init__(self, start_date: datetime):
        self.fact_history = []
        self.current_date = start_date
    
    def check_fact(self, fact: str) -> Optional[str]:
        """
        Checks if the given fact is valid based on predefined rules.
        
        Args:
            fact (str): The fact to be checked.

        Returns:
            Optional[str]: A message indicating the result of the validation or None if invalid.
        """
        # Example rule: Facts mentioning today's date are not considered valid
        if "today" in fact.lower():
            self.fact_history.append(f"{fact} - Invalid: Contains 'today'")
            return f"'{fact}' is invalid as it contains 'today'. Please use a specific date."
        
        # Example rule: Facts must be about events that have already occurred, not future
        if "will happen" in fact.lower():
            self.fact_history.append(f"{fact} - Invalid: Uses the phrase 'will happen'")
            return f"'{fact}' is invalid as it uses the phrase 'will happen'. Please use a past tense."
        
        # Example rule: Facts must be about recent events
        if (self.current_date - datetime.strptime(fact.split()[0], '%Y-%m-%d')).days > 7:
            self.fact_history.append(f"{fact} - Invalid: Event occurred more than 7 days ago")
            return f"'{fact}' is invalid as the event it refers to occurred more than 7 days ago."
        
        # If no issues, mark the fact as valid
        self.fact_history.append(fact)
        return None

    def get_history(self) -> List[str]:
        """
        Returns a list of checked facts and their validation status.
        
        Returns:
            List[str]: A list containing details about each fact's check.
        """
        return self.fact_history


# Example usage
if __name__ == "__main__":
    start_date = datetime(2023, 1, 1)
    fact_checker = FactChecker(start_date)
    
    # Test facts
    facts_to_check = [
        "Today is a sunny day",
        "The meeting will happen on February 5th",
        "Yesterday's sales figures were impressive - 500 units sold"
    ]
    
    for fact in facts_to_check:
        result = fact_checker.check_fact(fact)
        if result:
            print(result)
```

This example creates a `FactChecker` class that validates simple string-based facts using basic rules. The rules are hard-coded and cover some common issues with reasoning sophistication, such as checking the date mentioned in a fact is not too old or future-oriented.