SvgFont = ref object
  unitsPerEm*, ascent*, descent*: float32
  advances: Table[Rune, float32]
  glyphPaths: Table[Rune, Path]
  kerningPairs: Table[(Rune, Rune), float32]
  missingGlyphAdvance: float32
  missingGlyphPath: Path

proc getAdvance(svgFont: SvgFont; rune: Rune): float32 {....raises: [], tags: [].}

proc getGlyphPath(svgFont: SvgFont; rune: Rune): Path {....raises: [], tags: [].}

proc getKerningAdjustment(svgFont: SvgFont; left, right: Rune): float32 {.
    ...raises: [], tags: [].}

proc hasGlyph(svgFont: SvgFont; rune: Rune): bool {....raises: [], tags: [].}

proc parseSvgFont(buf: string): SvgFont {....raises: [PixieError],
    tags: [ReadIOEffect, RootEffect, WriteIOEffect].}