@staticmethod
def merge_kwargs(kwargs, key, value):
    """
        set the kwargs key/value pair, joining any pre-existing value with
        a space.

        :param kwargs: keyword arguments
        :type kwargs: dict
        :param key: key
        :type key: str
        :param value: the value to set the kwarg to
        :type value: object
        """
    if key is not None:
        if key in kwargs:
            value = ' '.join([kwargs[key], value])
        kwargs[key] = value
