# kerning: Support for accessing kerning data

fontTools.ufoLib.kerning.lookupKerningValue(pair, kerning, groups, fallback=0, glyphToFirstGroup=None, glyphToSecondGroup=None)

  Note: This expects kerning to be a flat dictionary of kerning pairs, not the nested structure used in kerning.plist.

      >>> groups = {
      ...     "public.kern1.O" : ["O", "D", "Q"],
      ...     "public.kern2.E" : ["E", "F"]
      ... }
      >>> kerning = {
      ...     ("public.kern1.O", "public.kern2.E") : -100,
      ...     ("public.kern1.O", "F") : -200,
      ...     ("D", "F") : -300
      ... }
      >>> lookupKerningValue(("D", "F"), kerning, groups)
      -300
      >>> lookupKerningValue(("O", "F"), kerning, groups)
      -200
      >>> lookupKerningValue(("O", "E"), kerning, groups)
      -100
      >>> lookupKerningValue(("O", "O"), kerning, groups)
      0
      >>> lookupKerningValue(("E", "E"), kerning, groups)
      0
      >>> lookupKerningValue(("E", "O"), kerning, groups)
      0
      >>> lookupKerningValue(("X", "X"), kerning, groups)
      0
      >>> lookupKerningValue(("public.kern1.O", "public.kern2.E"),
      ...     kerning, groups)
      -100
      >>> lookupKerningValue(("public.kern1.O", "F"), kerning, groups)
      -200
      >>> lookupKerningValue(("O", "public.kern2.E"), kerning, groups)
      -100
      >>> lookupKerningValue(("public.kern1.X", "public.kern2.X"), kerning, groups)
      0