def METHOD_NAME(self, s=b""):
    while True:  # read until next whitespace
        c = self.fp.read(1)
        if not c or c in b_whitespace:
            break
        if c > b"\x79":
            raise ValueError("Expected ASCII value, found binary")
        s = s + c
        if len(s) > 9:
            raise ValueError("Expected int, got > 9 digits")
    return s