def get_deployment_dates(config, state):
    """ Using input parameters get the range of years and months available
        for company/ crew deployment. If non are specified, set to the
        number of years within simulation and all months. defaults to
        All years within simulation and all months if not specified.
    """
    # if user does not specify deployment interval, set to all months/years
    if len(config['scheduling']['deployment_years']) > 0:
        deployment_years = config['scheduling']['deployment_years']
    else:
        deployment_years = list(
            range(state['t'].start_date.year, state['t'].end_date.year+1))

    if len(config['scheduling']['deployment_months']) > 0:
        deployment_months = config['scheduling']['deployment_months']
    else:
        deployment_months = list(range(1, 13))
    return deployment_years, deployment_months