How do I set custom axis titles for a go.Figure()?

I have a graph objects Figure and I want to set custom axis titles. I've found how to do it with update_layout() for plotly express figures, but I haven't found a way to do it with a go.Figure(). (Using that instead of a plotly express graph because I'm not sure how to graph an exponential function using plotly express.)

Code:

import numpy as np
import plotly.graph_objects as go
import plotly.io as pio
pio.templates.default = "none"

x = np.linspace(0, 10,100)

graph = go.Scatter(x=x, y=100*pow(1/2, x), 
                      mode='lines', 
                      line_width=2, line_color='red',)

layout = go.Layout(title='My Graph')

fig = go.Figure(data=[graph], layout=layout)

# want to set axis titles!

fig.show()

How can I set custom axis titles?

To set a custom title you can configure a dictionary for the "xaxis" or "yaxis" property of go.Layout()

import numpy as np
import plotly.graph_objects as go
import plotly.io as pio
pio.templates.default = "none"

x = np.linspace(0, 10,100)

graph = go.Scatter(x=x, y=100*pow(1/2, x), 
                      mode='lines', 
                      line_width=2, line_color='red',)

layout = go.Layout(
    title='My Graph', 
    xaxis={
        "title" : {
            "text" : "My custom x axis title"
        },
    },
    yaxis={
        "title" : {
            "text" : "My custom y axis title"
        }
    }
)

fig = go.Figure(data=[graph], layout=layout)



fig.show()

another valid notion would be:

import numpy as np
import plotly.graph_objects as go
import plotly.io as pio
pio.templates.default = "none"

x = np.linspace(0, 10,100)

graph = go.Scatter(x=x, y=100*pow(1/2, x), 
                      mode='lines', 
                      line_width=2, line_color='red',)

layout = go.Layout(
    title='My Graph', 
    xaxis=dict(
        title=dict(text="My custom x axis title")
    ),
    yaxis=dict(
        title=dict(text="My custom y axis title")
    )
)

fig = go.Figure(data=[graph], layout=layout)


fig.show()