hello,I want ask: What do you mean by a few 'parent' and 'ids' here?

[tianyi725]

.kv file
`

<NumberButton@Button>:
on_release: self.parent.parent.ids.calc_input.text += self.text
size_hint: None, None
font_size: self.parent.parent.button_font_size
width: self.parent.parent.button_width
height: self.parent.parent.button_height

<Calculator_Widget>:
RowLayout:
    RowLayout:
        NumberButton:
        text: '1'
        NumberButton:
        text: '2'
        NumberButton:
        text: '3'

`

What do you mean by a few ‘parent’ and ‘ids here?
I don't know how to understand 'parent' and 'ids'
thank you!

In addition:
I put it here
Self.parent.parent.ids.calc_input.text + = self.text
Change into
Root.ids.calc_input.text + = self.text
or
Root.parent.parent.ids.calc_input.text + = self.text
Will it go wrong?