"""Create fact_checker
Generated by Phi-Octopus Eden
2025-11-06 03:23:28.920374
"""

```python
from typing import List, Set
from collections import defaultdict

class FactChecker:
    """
    A class that implements a basic fact-checking mechanism to verify the truthfulness of statements.
    """

    def __init__(self):
        self.knowledge_base: Set[str] = set()
    
    def add_statement(self, statement: str) -> None:
        """
        Adds a new statement to the knowledge base.

        :param statement: A string representing the statement to be added.
        """
        if statement not in self.knowledge_base:
            self.knowledge_base.add(statement)
    
    def check_fact(self, fact_to_check: str) -> bool:
        """
        Checks whether a given fact is present in the knowledge base.

        :param fact_to_check: A string representing the fact to be checked.
        :return: True if the fact is true (present), False otherwise.
        """
        return fact_to_check in self.knowledge_base
    
    def generate_report(self, facts: List[str]) -> int:
        """
        Generates a report indicating how many of the given facts are present in the knowledge base.

        :param facts: A list of strings representing the facts to be checked against the knowledge base.
        :return: The number of true facts found.
        """
        true_count = 0
        for fact in facts:
            if self.check_fact(fact):
                true_count += 1
        return true_count

# Example usage:
if __name__ == "__main__":
    checker = FactChecker()
    # Adding some statements to the knowledge base
    checker.add_statement("The sky is blue.")
    checker.add_statement("Water boils at 100 degrees Celsius.")
    
    # Checking facts
    print(checker.check_fact("The sky is green."))  # Should return False
    print(checker.check_fact("The sky is blue."))   # Should return True
    
    # Generating a report for multiple facts
    test_facts = ["The sky is green.", "Water boils at 100 degrees Celsius.", "Gravity pulls objects towards Earth."]
    result = checker.generate_report(test_facts)
    print(f"Number of true facts: {result}")  # Should return 2
```