def _is_appendable(file_like):
    if file_like.seekable() and file_like.tell() != 0:
        if "<stdout>" == getattr(file_like, "name", ""):
            # In OSX, sys.stdout is seekable and has a non-zero tell() but
            # we wouldn't want to append to a stdout. In the python REPL,
            # sys.stdout is named `<stdout>`
            return False
        if file_like.readable():
            return True
        else:
            raise ValueError(
                "When appending to an avro file you must use the "
                + "'a+' mode, not just 'a'"
            )
    else:
        return False