"""Create fact_checker
Generated by Phi-Octopus Eden
2025-11-08 06:15:25.095860
"""

```python
from typing import List


class FactChecker:
    """
    A basic fact-checking class that evaluates statements against a predefined knowledge base.
    """

    def __init__(self, knowledge_base: List[str]):
        self.knowledge_base = set(knowledge_base)

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

        :param statement: A string representing a fact or statement.
        :return: True if the statement is found in the knowledge base, False otherwise.
        """
        return statement.lower() in self.knowledge_base

    def add_fact(self, new_fact: str) -> None:
        """
        Adds a new fact to the knowledge base.

        :param new_fact: A string representing a new fact to be added.
        """
        if new_fact not in self.knowledge_base:
            self.knowledge_base.add(new_fact.lower())

    def remove_fact(self, old_fact: str) -> None:
        """
        Removes an existing fact from the knowledge base.

        :param old_fact: A string representing a fact to be removed.
        """
        if old_fact.lower() in self.knowledge_base:
            self.knowledge_base.remove(old_fact.lower())

    def list_facts(self) -> List[str]:
        """
        Lists all facts currently stored in the knowledge base.

        :return: A list of strings, each representing a fact.
        """
        return sorted(list(self.knowledge_base))


# Example usage
if __name__ == "__main__":
    # Initialize with some known facts
    checker = FactChecker(["the earth orbits the sun", "water boils at 100 degrees Celsius"])

    print("Is 'the moon is a planet' true? ", checker.check_fact("The Moon is a Planet"))  # False

    checker.add_fact("dogs are mammals")
    print("After adding fact, is 'dogs are mammals' true? ", checker.check_fact("Dogs are mammals"))  # True

    checker.remove_fact("the earth orbits the sun")
    print("After removing fact, is 'the earth orbits the sun' still in knowledge base? ",
          "The Earth Orbits The Sun" in checker.list_facts())  # False
```