Method columns

crates/ruff_python_formatter/src/string/docstring.rs:1716–1728

Returns the indentation's visual width in columns/spaces. For docstring indentation, black counts spaces as 1 and tabs by increasing the indentation up to the next multiple of 8. This is effectively a port of [`str.expandtabs`](https://docs.python.org/3/library/stdtypes.html#str.expandtabs), which black [calls with the default tab width of 8](https://github.com/psf/black/blob/c36e468794f9256d5e92

(self)

    /// [`str.expandtabs`](https://docs.python.org/3/library/stdtypes.html#str.expandtabs),
    /// which black [calls with the default tab width of 8](https://github.com/psf/black/blob/c36e468794f9256d5e922c399240d49782ba04f1/src/black/strings.py#L61).
    const fn columns(self) -> usize {
        match self {
            Self::Spaces(count) => count,
            Self::Tabs(count) => count * Self::TAB_INDENT_WIDTH,
            Self::TabSpaces { tabs, spaces } => tabs * Self::TAB_INDENT_WIDTH + spaces,
            Self::SpacesTabs { spaces, tabs } => {
                let mut indent = spaces;
                indent += Self::TAB_INDENT_WIDTH - indent.rem_euclid(Self::TAB_INDENT_WIDTH);
                indent + (tabs - 1) * Self::TAB_INDENT_WIDTH
            }
            Self::Mixed { width, .. } => width,
        }
    }

    /// Returns the length of the indentation in bytes.
    ///