function IsAttached(a_World, a_BlockX, a_BlockY, a_BlockZ, a_RequiredMeta)
   local Block, Meta = a_World:GetBlockTypeMeta(a_BlockX, a_BlockY, a_BlockZ)
   if ((Block == E_BLOCK_TORCH) or (Block == E_BLOCK_STONE_BUTTON)) then
      -- return true if the meta is correct
   end
   return false
end


function OnPlayerLeftClick(a_Player, X, Y, Z)
   local World = a_Player:GetWorld()
   -- I used some random numbers as meta value
   if (not IsAttached(World, X + 1, Y, Z, 5) and
       not IsAttached(World, X - 1, Y, Z, 2) and 
       not IsAttached(World, X, Y, Z + 1, 1) and
       not IsAttached(World, X, Y, Z - 1, 0)
   ) then
      -- Block is not attached, bail out.
      return false
   end
   -- Do whatever you want to do if there is a torch or button attached
end