How to use the gatsby-design-tokens.colors.purple function in gatsby-design-tokens

navigation: {
    background: hex2rgba(c.white, 0.985),
    linkDefault: c.grey[70],
    linkActive: c.purple[50],
    linkHover: c.gatsby,
    socialLink: c.grey[40],
  },
  search: {
    suggestionHighlightBackground: c.lavender,
    suggestionHighlightColor: c.gatsby,
  },
  sidebar: {
    itemHoverBackground: hex2rgba(c.purple[20], 0.275),
    itemBackgroundActive: `transparent`,
    itemBorderColor: `transparent`, // `rgba(0,0,0,0.05)`,
    activeSectionBackground: hex2rgba(c.purple[20], 0.15),
    itemBorderActive: c.purple[10],
  },
  themedInput: {
    background: c.grey[10],
    backgroundFocus: c.white,
    focusBorder: c.purple[60],
    focusBoxShadow: c.purple[30],
    icon: c.grey[50],
    iconFocus: c.grey[60],
    placeholder: c.grey[60],
  },
  widget: {
    background: c.white,
    color: c.text.primary,
  },
  newsletter: {

const col = {
  ...c,
  // https://theme-ui.com/theme-spec#color
  // Theme-UI required keys
  //
  // Body foreground color
  // overwrite what's currently in `colors` from `gatsby-design-tokens`
  // also see `heading` key below
  text: c.grey[80], // c.text.primary
  // Body background color
  background: c.white,
  // Primary brand color for links, buttons, etc.
  primary: c.gatsby,
  // A secondary brand color for alternative styling
  secondary: c.purple[40],
  // A contrast color for emphasizing UI
  accent: c.orange[60],
  // A faint color for backgrounds, borders, and accents that do not require high contrast with the background color
  muted: c.grey[5],
  // end Theme-UI required keys
  banner: c.purple[70],
  // gatsby-design-tokens has the following in colors.text,
  // which conflicts with theme-ui's default color `text`
  // making text.header and text.secondary available as
  // `heading` and `textMuted` resolves that
  heading: c.text.header, // text.header
  textMuted: c.text.secondary, // text.secondary
  // moved `text.placeholder` to `input.placeholder`
  // ref. e.g. https://github.com/system-ui/theme-ui/blob/702c43e804046a94389e7a12a8bba4c4f436b14e/packages/presets/src/tailwind.js#L6
  // transparent: `transparent`,
  // expand `gatsby-design-tokens` defaults