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: complain.rb
    path of file: ./repos/jruby/spec/mspec/lib/mspec/matchers
    
    the code of the file until where you have to start completion: require 'mspec/helpers/io'

class ComplainMatcher
  def initialize(complaint = nil, options 
    
  def matches?(proc)
    @saved_err = $stderr
    @verbose = $VERBOSE
    err = IOStub.new

    $stderr = err
    $VERBOSE = @options.key?(:verbose) ? @options[:verbose] : false
    begin
      proc.call
    ensure
      $VERBOSE = @verbose
      $stderr = @saved_err
    end