output = Path("error-bar-add.png")
fig.savefig(output, dpi=160)
plt.close(fig)

pixels = mpimg.imread(output)
symmetric_directions = len(symmetric.lines[2])
asymmetric_directions = len(asymmetric.lines[2])

if symmetric_directions != 1:
    raise RuntimeError("symmetric error bars were not created")
if asymmetric_directions != 2:
    raise RuntimeError("horizontal and vertical error bars were not created")

print(f"symmetric error directions: {symmetric_directions}")
print(f"asymmetric error directions: {asymmetric_directions}")
print(f"image shape: {pixels.shape[0]} x {pixels.shape[1]} x {pixels.shape[2]}")
print(f"saved: {output}")