我想索引numpy数组中的所有元素，并在末尾包含第一个索引。所以如果我有一个数组[2, 4, 6]，我想索引这个数组，结果是[2, 4, 6, 2]。

import numpy as np
a = np.asarray([2,4,6])

# One solution is 
cycle = np.append(a, a[0])

# Another solution is 
cycle = a[[0, 1, 2, 0]]

# Instead of creating a list, can indexing type be combined?
cycle = a[:+0]