def add_arrow(ax: Axes3D, vec3, **kwargs):
arrow_kwargs = {
"mutation_scale": 20,
"lw": 3,
"arrowstyle": "-|>",
"color": "r"
}
arrow_kwargs.update(kwargs)
a = Arrow3D(*[(0, v) for v in vec3], **arrow_kwargs)
ax.add_artist(a)
return a
