title: Step in Python Lettuce. Is it possible to prepend step.hashes headers in step code?
body: <p>Currently I'm writting some integration tests in Python Lettuce. I want to create a generic step for some XML's comparision. </p>
  
  <p>I know that in .feature file after step definition like</p>
  
  <pre><code>Scenario: I want to compare XML's...
   ...
   And I check generated transaction "XYZ" contents with parameters:
   ...
  </code></pre>
  
  <p>I can add step.hashes, which would be available in step.hashes property in step definition (some_step_definitions.py bellow)</p>
  
  <pre><code>@step(u'And I check generated transaction "([^"]+)" contents with parameters:$')
  def check_generated_content(step, transaction_type):
      *(some xml mappings for comparision, appending dictionaries to step.hashes)*
      for item in mappings:
         step.hashes.append({
            'key1': 'val1',
            'key2': 'val2'
         })
  </code></pre>
  
  <p>My question is: Is it possible to append headers (key1, key2) in step code (check_generated_content), that when tests are executed I have headers in test report like:</p>
  
  <pre><code>Scenario: I want to compare XML's...
   ...
   And I check generated transaction "XYZ" contents with parameters:
  | key1 | key2 |
  | val1 | val2 |
  ...
  </code></pre>
  
  <p>When I dont specify </p>
  
  <pre><code>And I check generated transaction "XYZ" contents with parameters:
  | key1 | val1 |
  </code></pre>
  
  <p>in feature file, I get in test report:</p>
  
  <pre><code>And I check generated transaction "XYZ" contents with parameters:
  | | |
  | | |
  </code></pre>
  
  <p>In conclusion.. I would like to write only</p>
  
  <pre><code>And I check generated transaction "XYZ" contents with parameters:
  </code></pre>
  
  <p>instead of </p>
  
  <pre><code>And I check generated transaction "XYZ" contents with parameters:
  | key1 | val1 |
  </code></pre>
  
  <p>every time.</p>