Adds a key to a sppasBaseOption.
- author: Brigitte Bigi
- organization: Laboratoire Parole et Langage, Aix-en-Provence, France
- contact: contact@sppas.org
- license: GPL, v3
- copyright: Copyright (C) 2011-2019 Brigitte Bigi

Adds a key to a sppasBaseOption.
Create a sppasOption instance.
def __init__(self, option_key, option_type='str', option_value=''):
    """Create a sppasOption instance.
    :param option_key: (any type) An identifier for that option.
    :param option_type: (str) Type of the option.
    :param option_value: (str) The value of the option.
    """
    super(sppasOption, self).__init__(option_type, option_value)
    self._key = option_key
Return the key of that option.
def get_key(self):
    """Return the key of that option."""
    return self._key