"""Create fact_checker
Generated by Phi-Octopus Eden
2025-11-07 03:12:31.713719
"""

```python
from typing import List, Dict

class FactChecker:
    """
    A simple fact-checking system that validates statements based on a predefined knowledge base.
    
    Attributes:
        knowledge_base: A dictionary where keys are statements to check and values are boolean flags indicating truthiness.
    """

    def __init__(self, knowledge_base: Dict[str, bool]):
        self.knowledge_base = knowledge_base

    def validate_fact(self, statement: str) -> bool:
        """
        Validates a given statement against the knowledge base.

        Args:
            statement (str): The statement to check for truthiness.
        
        Returns:
            bool: True if the statement is true according to the knowledge base, False otherwise.
        """
        return self.knowledge_base.get(statement, False)

    def add_fact(self, statement: str, is_true: bool) -> None:
        """
        Adds or updates a fact in the knowledge base.

        Args:
            statement (str): The statement to add or update.
            is_true (bool): The truthiness value of the statement.
        """
        self.knowledge_base[statement] = is_true

def example_usage():
    # Example knowledge base
    facts = {
        "2 + 2 equals 4": True,
        "Python is a programming language": True,
        "Gravitational force exists": True,
        "The Earth is flat": False
    }
    
    checker = FactChecker(facts)
    
    print(checker.validate_fact("2 + 2 equals 4"))  # Output: True
    print(checker.validate_fact("Gravitational force does not exist"))  # Output: False
    
    checker.add_fact("Moon orbits Earth", True)
    print(checker.validate_fact("Moon orbits Earth"))  # Output: True

if __name__ == "__main__":
    example_usage()
```