"""Create fallback_executor
Generated by Phi-Octopus Eden
2025-11-06 22:19:17.058181
"""

```python
from typing import Callable, Optional


class FallbackExecutor:
    """
    A class for executing a primary function with fallback execution in case of errors.
    
    Attributes:
        primary_func (Callable): The main function to be executed.
        fallback_func (Optional[Callable]): The function to be used as a fallback if an error occurs in the primary function.
        
    Methods:
        execute: Attempts to run the primary function and switches to the fallback function on any exception.
    """
    
    def __init__(self, primary_func: Callable, fallback_func: Optional[Callable] = None):
        self.primary_func = primary_func
        self.fallback_func = fallback_func
    
    def execute(self) -> Optional[str]:
        """Executes the primary function or the fallback function if an exception is raised."""
        try:
            result = self.primary_func()
            return str(result)
        except Exception as e:
            print(f"An error occurred: {e}")
            if self.fallback_func:
                try:
                    fallback_result = self.fallback_func()
                    return str(fallback_result)
                except Exception as fe:
                    print(f"Fallback function also failed: {fe}")
                    return None
            else:
                print("No fallback function available.")
                return None


# Example usage

def divide_and_greet(x: int, y: int) -> Optional[str]:
    """
    Divides two numbers and returns the result with a greeting message.
    
    Args:
        x (int): The numerator.
        y (int): The denominator.
        
    Returns:
        str: A string containing the division result and a greeting.
    """
    try:
        return f"Result of {x} / {y} is {x / y}"
    except ZeroDivisionError as e:
        raise ValueError("Cannot divide by zero") from e


def greet_user() -> Optional[str]:
    """Greets the user."""
    return "Hello, welcome to our service!"


# Creating a FallbackExecutor instance
executor = FallbackExecutor(primary_func=divide_and_greet, fallback_func=greet_user)

# Example 1: Normal execution with valid inputs
print(executor.execute())  # Should print the result and greeting

# Example 2: Handling division by zero error
print(executor.execute(x=10, y=0))  # Should switch to the fallback function and greet the user

```