code: def to_glyphs_blue_values(self, ufo, master):
      
  
      zones = []
      blue_values = _pairs(ufo.info.postscriptBlueValues)
      other_blues = _pairs(ufo.info.postscriptOtherBlues)
      for y1, y2 in blue_values:
          size = y2 - y1
          if y2 == 0:
              pos = 0
              size = -size
          else:
              pos = y1
          zones.append(self.glyphs_module.GSAlignmentZone(pos, size))
      for y1, y2 in other_blues:
          size = y1 - y2
          pos = y2
          zones.append(self.glyphs_module.GSAlignmentZone(pos, size))
  
      master.alignmentZones = sorted(zones, key=lambda zone: -zone.position)
docs: Sets the GSFontMaster alignmentZones from the postscript blue values.