在下面的代码中，我画了一条线，然后在它上面画了一个不透明的补丁（alpha=1）。我希望被补丁覆盖的那部分线被隐藏起来，但它看起来就像是在补丁之后画的线。如何改变它，使线不显示出来？

代码改编自这个matplotlib示例

import matplotlib.path as mpath
import matplotlib.patches as mpatches
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
Path = mpath.Path
path_data = [
    (Path.MOVETO, (1.58, -2.57)),
    (Path.CURVE4, (0.35, -1.1)),
    (Path.CURVE4, (-1.75, 2.0)),
    (Path.CURVE4, (0.375, 2.0)),
    (Path.LINETO, (0.85, 1.15)),
    (Path.CURVE4, (2.2, 3.2)),
    (Path.CURVE4, (3, 0.05)),
    (Path.CURVE4, (2.0, -0.5)),
    (Path.CLOSEPOLY, (1.58, -2.57)),
    ]
codes, verts = zip(*path_data)
path = mpath.Path(verts, codes)
# plot control points and connecting lines
x, y = zip(*path.vertices)
y2 = [_y-1 for _y in y]
line, = ax.plot(x, y2, 'go-')
patch = mpatches.PathPatch(path, facecolor='r', alpha=1)
ax.add_patch(patch)
ax.grid()
ax.axis('equal')
plt.show()