title: Can I alias RSpec matchers?
body: <p>I've got these two matchers that are identical apart from their names:</p>
  
  <pre><code>RSpec::Matchers.define :be_the_downcased_version_of do |actual|
      match do |actual|
          @actual = actual
          @expected = expected
  
          @actual == @expected.downcase
      end
  
      failure_message do |actual|
          "Expected #{@actual.inspect} to be the downcased version of #{expected.inspect}.\nIt was not: #{@actual.inspect}"
      end
  
      failure_message_when_negated do |actual|
          "Expected #{@actual.inspect} to not be the downcased version of #{expected.inspect}.\nIt was: #{@actual.inspect}"
      end
  
      description do
          "be the downcased version of #{expected.inspect}"
      end
  end
  
  RSpec::Matchers.define :return_the_downcased_version_of do |actual|
      match do |actual|
          @actual = actual
          @expected = expected
  
          @actual == @expected.downcase
      end
  
      failure_message do |actual|
          "Expected #{@actual.inspect} to be the downcased version of #{expected.inspect}.\nIt was not: #{@actual.inspect}"
      end
  
      failure_message_when_negated do |actual|
          "Expected #{@actual.inspect} to not be the downcased version of #{expected.inspect}.\nIt was: #{@actual.inspect}"
      end
  
      description do
          "be the downcased version of #{expected.inspect}"
      end
  end
  </code></pre>
  
  <p>Can I alias them like when aliasing a method with Ruby?</p>
  
  <pre><code>alias_method :foo_meth, :bar_meth
  </code></pre>