You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: matches-compare.rb
    path of file: ./repos/genometools/scripts
    
    the code of the file until where you have to start completion: #!/usr/bin/env ruby

require "set"
require "optparse"
require_relative "SEmatch"

def add_single_match(
    
def merge_sets(mh0,mh1)
  seqnumpairkeys = (mh0.keys + mh1.keys).to_set
  seqnumpairkeys.each do |key|
    mh0_set = if mh0.has_key?(key) then mh0[key] else Set.new() end
    mh1_set = if mh1.has_key?(key) then mh1[key] else Set.new() end
    yield key, mh0_set, mh1_set
  end
end