def within_range(year_start, year_end, year_x):
    """
    Check if year_x is within the time span defined by [year_start, year_end]
    
    Parameters
    -----------
    year_start : int
    year_end : int
    year_x : int
    
    Return
    -------
    Boolean
    """
    return ((year_x >= year_start) and (year_end >= year_x))