level1_basic.py

class FileServer:
    def __init__(self):
        # TODO: initialize your data structure here
        pass
    
    def FILE_UPLOAD(self, file_name: str, size: int):
        """
        Upload a file to the server.
        - Raise RuntimeError if a file with the same name already exists.
        """
        # TODO: implement upload logic

    def FILE_GET(self, file_name: str):
        """
        Return the file size if it exists, or None if it does not.
        """
        # TODO: implement get logic

    def FILE_COPY(self, source: str, dest: str):
        """
        Copy the source file to dest.
        - Raise RuntimeError if the source file doesn't exist.
        - Overwrite dest if it already exists.
        """
        # TODO: implement copy logic