title: How to pass parameter to PythonOperator in Airflow
body: <p>I just started using <strong>Airflow</strong>, can anyone enlighten me how to pass a parameter into <strong>PythonOperator</strong> like below:</p>
  
  <pre><code>t5_send_notification = PythonOperator(
      task_id='t5_send_notification',
      provide_context=True,
      python_callable=SendEmail,
      op_kwargs=None,
      #op_kwargs=(key1='value1', key2='value2'),
      dag=dag,
  )
  
  def SendEmail(**kwargs):
      msg = MIMEText("The pipeline for client1 is completed, please check.")
      msg['Subject'] = "xxxx"
      msg['From'] = "xxxx"
      ......
      s = smtplib.SMTP('localhost')
      s.send_message(msg)
      s.quit()
  </code></pre>
  
  <p>I would like to be able to pass some parameters into the <code>t5_send_notification</code>'s callable which is <code>SendEmail</code>, ideally I want to attach the full log and/or part of the log (which is essentially from the kwargs) to the email to be sent out, guessing the <code>t5_send_notification</code> is the place to gather those information.</p>
  
  <p>Thank you very much.</p>