How to get the plotly theme as a dictionary?

I would like to have the definition of the plotly theme (or any other theme that comes with plotly for that reason) as a dictionary, i.e., in this format:

ggplot' : {
            'colorscale':'ggplot',
            'linewidth':1.3,
            'linecolor':'pearl',
            'bargap' : .01,
            'layout' : {
                'legend' : {'bgcolor':'white','font':{'color':'grey10'}},
                'paper_bgcolor' : 'white',
                'plot_bgcolor' : 'grey14',
                'yaxis' : {
                    'tickfont' : {'color':'grey10'},
                    'gridcolor' : 'lightivory',
                    'titlefont' : {'color':'grey10'},
                    'zerolinecolor' : 'lightivory',
                    'showgrid' : True
                },
                'xaxis' : {
                    'tickfont' : {'color':'grey10'},
                    'gridcolor' : 'lightivory',
                    'titlefont' : {'color':'grey10'},
                    'zerolinecolor' : 'lightivory',
                    'showgrid' : True
                },
                'titlefont' : {'color':'charcoal'}
            },
            'annotations' : {
                'fontcolor' : 'grey10',
                'arrowcolor' : 'grey10'
            }

In other words, I would like to know the specs of the theme.

How I can get this information?