Transform a dictionary of {name: [(elt, value)+]} (resulting from
        get_properties) to a dictionary of {name, value} where names are first
        encountered in input properties.

    :param dict properties: properties to firsts.
    :return: dictionary of parameter values by names.
    :rtype: dict

def firsts(properties):
    """
    Transform a dictionary of {name: [(elt, value)+]} (resulting from
        get_properties) to a dictionary of {name, value} where names are first
        encountered in input properties.

    :param dict properties: properties to firsts.
    :return: dictionary of parameter values by names.
    :rtype: dict
    """

    result = {}

    # parse elts
    for name in properties:
        elt_properties = properties[name]
        # add property values in result[name]
        result[name] = elt_properties[0][1]

    return result