How to use the gatsby-design-tokens.lineHeights.default function in gatsby-design-tokens

let fontsTokens = {}
for (let fontFamily in f) {
  fontsTokens[fontFamily] = f[fontFamily].join(`, `)
}
// https://theme-ui.com/theme-spec#typography
// TODO adjust keys in gatsby-design-tokens
fontsTokens.body = fontsTokens.system
fontsTokens.heading = fontsTokens.header

const fontSizesTokens = fs.map(token => `${token / 16}rem`)
const spaceTokens = sp.map(token => `${token / 16}rem`)

const lineHeightsTokens = {
  ...lh,
  body: lh.default,
  heading: lh.dense,
}

const darkBackground = `#131217` // meh
const darkBorder = c.grey[90]
// const darkBackground = c.purple[90]
// const darkBorder = c.purple[80]
const shadowDarkBase = `19,18,23`
const shadowDarkFlares = `0,0,0`

const fweights = {
  body: fw[0],
  bold: fw[1],
  medium: `600`,
  heading: fw[1],
  headingPrimary: fw[2],