title: RSpec starts_with matcher variant using regular expressions
body: <p>Is there a variant of the RSpec <code>start_with</code> matcher that will use regular expression matching instead of equality when examining arrays of strings?  (I don't mind writing my own; but I don't want to re-invent the wheel.)</p>
  
  <p>Specifically, I want to have a spec that looks like this:</p>
  
  <pre><code>it 'begins with the standard header' do
    output = method_under_test
    # output is an array of Strings
    expect(output).to start_with([/foo/, /bar/])
  end
  </code></pre>
  
  <p>This spec should pass if <code>output[0]</code> matches <code>/foo/</code> and <code>output[1]</code> matches <code>/bar/</code>.</p>
  
  <p>Assuming I do need to write my own matcher, is there a way to "overload" <code>start_with</code>, or do I need to choose a different name?</p>