title: More pythonic way of checking if user input exists and consists of integers
body: <p>I have a GUI where I ask the user to enter some values. When the user submits the data I do some validation:</p>
  
  <ol>
  <li>first I check if the user has entered a value for each input</li>
  <li>then I check if each of the inputted values are integers</li>
  </ol>
  
  <p>Trying not to repeat myself to much I came up with this, but the second part of the validation looks more like a hack. Is there a more pythonic way of rewriting this, short of spelling everything out like in the first part of the validation?</p>
  
  <pre><code>    errors = []
      # 1) check if values exist
      if not self.startInput.GetValue():
          errors.append("Please provide a start")
      if not self.stopInput.GetValue():
          errors.append("Please provide a stop")
      if not self.valueInput.GetValue():
          errors.append("Please provide a value")
      # 2) check if values are integers
      try:
          self.start = int(self.startInput.GetValue())
          self.stop = int(self.stopInput.GetValue())
          self.value = int(self.valueInput.GetValue())
      except ValueError as err:
          tb = traceback.format_exc()
          func = re.search('self\.(.*) =', tb).groups()[0]
          errors.append("Value for {0} needs to be an integer.".format(func)) 
      if errors:
          raise RuntimeError('\n'.join(errors))
  </code></pre>