module Steep::AST::Types::Helper::ChildrenLevel

def level_of_children(children)
  levels = children.map(&:level)
  children.map(&:level).sort {|a, b| (b.size <=> a.size) || 0 }.inject() do |a, b|
    a.zip(b).map do |x, y|
      if x && y
        x + y
      else
        x || y || raise
      end
    end
  end || []
end