"""Base formatter class."""

from abc import ABC, abstractmethod
from typing import Any, Dict, List, TextIO


class OutputFormatter(ABC):
    """Abstract base class for output formatters."""

    def __init__(self, output: TextIO = None):
        self.output = output

    @abstractmethod
    def format(self, data: Any) -> str:
        """Format data for output."""
        pass

    def write(self, text: str) -> None:
        """Write to output stream."""
        if self.output:
            self.output.write(text)
        else:
            print(text, end="")

    def flush(self) -> None:
        """Flush output stream."""
        if self.output:
            self.output.flush()