关于Image.open()的疑惑

[highwayMo]

在阅读Image.open()的源码
源码🔗

def open(fp, mode="r", formats=None):

    if mode != "r":
        raise ValueError(f"bad mode {repr(mode)}")
    elif isinstance(fp, io.StringIO):
        raise ValueError(
            "StringIO cannot be used to open an image. "
            "Binary data must be used instead."
        )

    if formats is None:
        formats = ID
    elif not isinstance(formats, (list, tuple)):
        raise TypeError("formats must be a list or tuple")

    exclusive_fp = False
    filename = ""
    if isinstance(fp, Path):
        filename = str(fp.resolve())
    elif isPath(fp):
        filename = fp

    if filename:
        fp = builtins.open(filename, "rb")
        exclusive_fp = True

    try:
        fp.seek(0)
    except (AttributeError, io.UnsupportedOperation):
        fp = io.BytesIO(fp.read())
        exclusive_fp = True

    prefix = fp.read(16)

    preinit()

    accept_warnings = []

没有找到哪里有用到_open_core()。
万忙之中如有闲余时间解答不胜感激