"""Create fact_checker
Generated by Phi-Octopus Eden
2025-11-08 09:10:08.653063
"""

```python
from typing import List, Dict


class FactChecker:
    """
    A class for checking factual accuracy of statements.
    
    Attributes:
        knowledge_base (Dict[str, bool]): A dictionary storing known facts,
                                           where keys are statement strings and values are their correctness.
    
    Methods:
        add_fact: Adds a new fact to the knowledge base.
        check_statement: Checks if a given statement is correct based on the knowledge base.
    """
    
    def __init__(self):
        self.knowledge_base = {}
    
    def add_fact(self, statement: str, is_correct: bool) -> None:
        """Add a new factual statement to the knowledge base.

        Args:
            statement (str): The statement to be added.
            is_correct (bool): Whether the given statement is correct or not.
        
        Returns:
            None
        """
        self.knowledge_base[statement] = is_correct
    
    def check_statement(self, statement: str) -> bool:
        """Check if a given statement is in the knowledge base and its correctness.

        Args:
            statement (str): The statement to be checked.

        Returns:
            bool: True if the statement is correct according to the knowledge base, False otherwise.
        
        Raises:
            KeyError: If the statement does not exist in the knowledge base.
        """
        return self.knowledge_base[statement]


# Example usage
if __name__ == "__main__":
    fact_checker = FactChecker()
    
    # Adding facts to the knowledge base
    fact_checker.add_fact("Water boils at 100 degrees Celsius", True)
    fact_checker.add_fact("The Earth is flat", False)
    
    # Checking statements
    print(fact_checker.check_statement("Water boils at 100 degrees Celsius"))  # Expected: True
    print(fact_checker.check_statement("The Earth is round"))  # Not added, should raise KeyError
    try:
        print(fact_checker.check_statement("The Earth is round"))
    except KeyError as e:
        print(f"KeyError: {e}")
```

This code snippet demonstrates a basic fact-checking mechanism. It allows adding facts to a knowledge base and checking the correctness of given statements against that base. The example usage section shows how to use this class, including handling an attempt to check a statement not present in the knowledge base.