# File lib/ruote/exp/condition.rb, line 172
    def self.flatten_and_compare(tree)

      ftree = tree.flatten
      comparator = (ftree & COMPARATORS).first

      return nil unless comparator

      icomparator = ftree.index(comparator)
      left = ftree[0..icomparator - 1]
      right = ftree[icomparator + 1..-1]

      evl("#{flatten(left).inspect} #{comparator} #{flatten(right).inspect}")
    end