from abc import ABC, abstractmethod

class IOBuffer(ABC):
    """
    Abstract base class defining the interface for input/output operations.
    
    This interface allows for different implementations of IO handling,
    such as direct system IO or buffered web interface communication.
    """
    
    @abstractmethod
    def read(self) -> str:
        """
        Read and return available input.
        
        Should clear the input buffer after reading.
        
        Returns:
            str: Content from input buffer, or empty string if no input available
        """
        pass
        
    @abstractmethod
    def write(self, content: str) -> None:
        """
        Write content to output.
        
        Args:
            content: String content to write
        """
        pass
        
    @abstractmethod
    def buffer_length(self) -> int:
        """
        Get the current length of buffered input.
        
        Returns:
            int: Number of characters in the input buffer
        """
        pass