code: def findKnownKerningGroups(groups):
      """
      This will find kerning groups with known prefixes.
      In some cases not all kerning groups will be referenced
      by the kerning pairs. The algorithm for locating groups
      in convertUFO1OrUFO2KerningToUFO3Kerning will miss these
      unreferenced groups. By scanning for known prefixes
      this function will catch all of the prefixed groups.
  
      These are the prefixes and sides that are handled:
      @MMK_L_ - side 1
      @MMK_R_ - side 2
  
      >>> testGroups = {
      ...     "@MMK_L_1" : None,
      ...     "@MMK_L_2" : None,
      ...     "@MMK_L_3" : None,
      ...     "@MMK_R_1" : None,
      ...     "@MMK_R_2" : None,
      ...     "@MMK_R_3" : None,
      ...     "@MMK_l_1" : None,
      ...     "@MMK_r_1" : None,
      ...     "@MMK_X_1" : None,
      ...     "foo" : None,
      ... }
      >>> first, second = findKnownKerningGroups(testGroups)
      >>> sorted(first) == ['@MMK_L_1', '@MMK_L_2', '@MMK_L_3']
      True
      >>> sorted(second) == ['@MMK_R_1', '@MMK_R_2', '@MMK_R_3']
      True
      """
      knownFirstGroupPrefixes = ["@MMK_L_"]
      knownSecondGroupPrefixes = ["@MMK_R_"]
      firstGroups = set()
      secondGroups = set()
      for groupName in list(groups.keys()):
          for firstPrefix in knownFirstGroupPrefixes:
              if groupName.startswith(firstPrefix):
                  firstGroups.add(groupName)
                  break
          for secondPrefix in knownSecondGroupPrefixes:
              if groupName.startswith(secondPrefix):
                  secondGroups.add(groupName)
                  break
      return firstGroups, secondGroups
  
label_desc: Use image node_id 2 for calling a global function with example usage: findKnownKerningGroups(groups) and returns: firstGroups,  secondGroups