编写一个Python程序，计算一元二次方程的根（包括复数根）

import math

def quadratic(a, b, c):
    delta = b * b - 4 * a * c
    if delta < 0:
        realPart = -b / (2 * a)
        imagPart = math.sqrt(-delta) / (2 * a)
        print("该方程有两个复数根：")
        print("x1 = ", realPart, "+", imagPart, "i")
        print("x2 = ", realPart, "-", imagPart, "i")
    elif delta == 0:
        x = -b / (2 * a)
        print("该方程有一个实根：")
        print("x = ", x)
    else:
        x1 = (-b + math.sqrt(delta)) / (2 * a)
        x2 = (-b - math.sqrt(delta)) / (2 * a)
        print("该方程有两个实根：")
        print("x1 = ", x1)
        print("x2 = ", x2)

# 测试
quadratic(1, -2, 1) # delta = 0，有一个实根，x = 1.0
quadratic(1, 2, 1) # delta = 0，有一个实根，x = -1.0
quadratic(1, 1, 1) # delta < 0，有两个复数根，x1 = -0.5 + 0.8660254037844386i，x2 = -0.5 - 0.8660254037844386i
quadratic(1, -5, 6) # delta > 0，有两个实根，x1 = 3.0，x2 = 2.0