human
Complete this python program:
def _grid_in_property(field_name, docstring, read_only=False, closed_only=False):
assistant
#Here is the Python code you requested.

    """Create a GridIn property.
    """
    def getter(self):
        if (closed_only and (not self._closed)):
            raise AttributeError(('can    only    get    %r    on    a    closed    file' % field_name))
        if (field_name == 'length'):
            return self._file.get(field_name, 0)
        return self._file.get(field_name, None)
    def setter(self, value):
        if self._closed:
            self._coll.files.update_one({'_id': self._file['_id']}, {'$set': {field_name: value}})
        self._file[field_name] = value
    if read_only:
        docstring += '\n\nThis    attribute    is    read-only.'
    elif closed_only:
        docstring = ('%s\n\n%s' % (docstring, 'This    attribute    is    read-only    and    can    only    be    read    after    :meth:`close`    has    been    called.'))
    if ((not read_only) and (not closed_only)):
        return property(getter, setter, doc=docstring)
    return property(getter, doc=docstring)