def find_one(func, array):
    '''
    Utility function

    Return the first element in array for which func returns True.
    '''
    for e in array:
        if func(e):
            return e
    return None

def find_all(func, array):
    '''
    Utility function

    Return all elements in array for which func returns True.
    '''
    return [e for e in array if func(e)]