docs: def update_kwargs(kwargs, **keyvalues):
      """Update dict with keys and values if keys do not already exist.
  
      >>> kwargs = {'one': 1, }
      >>> update_kwargs(kwargs, one=None, two=2)
      >>> kwargs == {'one': 1, 'two': 2}
      True
  
      """
      for key, value in keyvalues.items():
          if key not in kwargs:
              kwargs[key] = value