"""Create fact_checker
Generated by Phi-Octopus Eden
2025-11-07 09:25:09.648706
"""

```python
from typing import List, Dict


class FactChecker:
    """
    A simple fact checker that evaluates statements based on a predefined knowledge base.
    The knowledge base consists of key-value pairs where keys are questions and values are answers.
    
    Attributes:
        knowledge_base (Dict[str, str]): A dictionary containing the knowledge base for evaluation.
    """

    def __init__(self, knowledge_base: Dict[str, str]):
        """
        Initializes the FactChecker with a given knowledge base.

        Args:
            knowledge_base (Dict[str, str]): The initial knowledge base for fact checking.
        """
        self.knowledge_base = knowledge_base

    def check_fact(self, statement: str) -> bool:
        """
        Checks if a given statement is true based on the knowledge base.

        Args:
            statement (str): A string representing the statement to be checked.

        Returns:
            bool: True if the statement is supported by the knowledge base, False otherwise.
        """
        return statement in self.knowledge_base and self.knowledge_base[statement] == 'True'

    def add_statement(self, question: str, answer: str) -> None:
        """
        Adds a new statement to the knowledge base.

        Args:
            question (str): The question part of the statement.
            answer (str): The answer part of the statement ('True' or 'False').
        """
        self.knowledge_base[question] = answer

    def update_statement(self, question: str) -> bool:
        """
        Updates an existing statement in the knowledge base if it exists.

        Args:
            question (str): The question part of the statement to be updated.

        Returns:
            bool: True if the statement was successfully updated, False otherwise.
        """
        return self.question_in_kb(question) and self.add_statement(question, 'True')

    def question_in_kb(self, question: str) -> bool:
        """
        Checks if a given question is in the knowledge base.

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

        Returns:
            bool: True if the question exists in the knowledge base, False otherwise.
        """
        return question in self.knowledge_base

    def list_statements(self) -> List[str]:
        """
        Lists all statements in the knowledge base.

        Returns:
            List[str]: A list of questions from the knowledge base.
        """
        return list(self.knowledge_base.keys())

# Example usage
if __name__ == "__main__":
    # Initialize fact checker with a simple knowledge base
    fact_checker = FactChecker({
        "Is Python a programming language?": 'True',
        "Does water boil at 100 degrees Celsius?": 'True'
    })

    print(fact_checker.check_fact("Is Python a programming language?"))  # True
    print(fact_checker.check_fact("Does Earth have only one moon?"))    # False

    fact_checker.add_statement("Is Brazil the largest country in South America?", "True")
    print(fact_checker.question_in_kb("Is Brazil the largest country in South America?"))  # True

    fact_checker.update_statement("Is Python a programming language?")
    print(fact_checker.check_fact("Is Python a programming language?"))  # True

    print(fact_checker.list_statements())  # List of all questions
```