Trying to write to a compressed zip file

zip.py

from io import RawIOBase
from zipfile import ZipFile, ZipInfo, ZIP_DEFLATED


class UnseekableStream(RawIOBase):
    def __init__(self):
        self._buffer = b''

    def writable(self):
        return True

    def write(self, b):
        if self.closed:
            raise ValueError('Stream was closed!')
        self._buffer += b
        return len(b)

    def get(self):
        chunk = self._buffer
        self._buffer = b''
        return chunk


def zipfile_generator(path, stream):
    # tried setting compresslevel as well, did not work
    with ZipFile(stream, mode='w', compression=ZIP_DEFLATED) as zf:
        z_info = ZipInfo.from_file(path)
        with open(path, 'rb') as entry, zf.open(z_info, mode='w') as dest:
            for chunk in iter(lambda: entry.read(16384), b''):
                dest.write(chunk)
                # Yield chunk of the zip file stream in bytes.
                yield stream.get()
    # ZipFile was closed.
    yield stream.get()


stream = UnseekableStream()
path = "small.csv"
with open("test.zip", "wb") as f:
    for i in zipfile_generator(path, stream):
        f.write(i)
stream.close()