ThemeRef = ref object
  name*: string
  colors*: Colors

proc newTheme(name: string; colors: Colors): ThemeRef {...}{.raises: [], tags: [].}

proc addTheme(theme: ThemeRef) {...}{.raises: [], tags: [].}

proc getTheme(name: string): ThemeRef {...}{.raises: [ResourceError], tags: [].}

proc `[]`(theme: ThemeRef; index: string): ColorRef {...}{.raises: [], tags: [].}

proc changeTheme(name: string) {...}{.raises: [ResourceError, KeyError], tags: [].}

macro `~`(theme: ThemeRef; field: untyped): untyped