Adding a "reset filter" option to a slider

[d-trigo]

Hi all, have a question regarding the slider interactivity feature: When I was experimenting with the multiple interactions example via the movies dataset I tried to see how the graph display would work if I wanted to create a single graph where multiple interactions can be used at the same time rather than how it worked in the 4x4 example where interactions applied to separate graphs. A feature I wanted to implement with this type of graph in turn is that any filter could be reset if the user opted to view films from all genres, years and/or ratings again. The main issue I'm encountering though is that although I think I've been able to correctly implement something along the lines of this for radio buttons and dropdown filters (barring inconsistent colors being introduced across years, which I believe I can fix), I'm not sure how to do it for sliders (which in this case is used to select films from a certain year). From the documentation I reviewed regarding sliders in particular, it seems like it will only take a range between a min and max without the ability to add a special index for "all" films but maybe there's a way to do it within that command or within a separate command that I'm missing. I'll paste a modified version of the multiple interactions example to show what I'm doing in terms of modifying the base graph and adding all interaction parameter. Thanks in advance to anybody reading:

import altair as alt
from vega_datasets import data

movies = alt.UrlData(
    data.movies.url,
    format=alt.DataFormat(parse={"Release_Date":"date"})
)

ratingfilters = ['G', 'NC-17', 'PG', 'PG-13', 'R'] #this is created separately for the Altair filter command, that way we're not selecting films with rating as "None"

ratings = ['G', 'NC-17', 'PG', 'PG-13', 'R', None] #this will be for the options available, None means all ratings

ratingslabels = ['G', 'NC-17', 'PG', 'PG-13', 'R', 'All'] #this creates the labels relative to the ratings list

genres = [
    None, 'Action', 'Adventure', 'Black Comedy', 'Comedy', #for the options bind with all genres as an option
    'Concert/Performance', 'Documentary', 'Drama', 'Horror', 'Musical',
    'Romantic Comedy', 'Thriller/Suspense', 'Western'
]

genrelabels = [
    'All', 'Action', 'Adventure', 'Black Comedy', 'Comedy', #"all" will select the None option
    'Concert/Performance', 'Documentary', 'Drama', 'Horror', 'Musical',
    'Romantic Comedy', 'Thriller/Suspense', 'Western'
]

base = alt.Chart(movies, width=200, height=200).mark_point(filled=True).transform_calculate(
    Rounded_IMDB_Rating = "floor(datum.IMDB_Rating)", 
    Hundred_Million_Production =  "datum.Production_Budget > 100000000.0 ? 1 : 0", #keeping this column calc. for posterity, but will not create a checkbox option for now
    Release_Year = "year(datum.Release_Date)", 
).transform_filter(
    alt.datum.IMDB_Rating > 0  
).transform_filter(
    alt.FieldOneOfPredicate(field='MPAA_Rating', oneOf=ratingfilters)
).encode(
    x=alt.X('Worldwide_Gross:Q').scale(domain=(100000,10**9), clamp=True), 
    y=alt.Y('IMDB_Rating:Q').scale(domain=(1,10)), #adding an explicit 1 to 10 scale just so it doesn't adjust during filters
    tooltip="Title:N" 
).properties(
    title="Multiple Interactions on One Graph Test"
)

# A dropdown filter
genre_dropdown = alt.binding_select(options=genres, labels=genrelabels, name="Genre") 
genre_select = alt.selection_point(fields=['Major_Genre'], bind=genre_dropdown) 

base = base.add_params(
    genre_select
).transform_filter(
    genre_select
) 

# A slider filter
year_slider = alt.binding_range(min=1969, max=2018, step=1, name="Release Year") #this is where i'm unclear as to how to add a reset filter-like option
slider_selection = alt.selection_point(bind=year_slider, fields=['Release_Year']) 

base = base.add_params( 
    slider_selection 
).transform_filter( 
    slider_selection
) 

#color changing marks
rating_radio = alt.binding_radio(options=ratings, labels=ratingslabels, name="Rating")
rating_select = alt.selection_point(fields=['MPAA_Rating'], bind=rating_radio)

rating_color_condition = alt.condition(
    rating_select,
    alt.Color('MPAA_Rating:N').legend(None),
    alt.value('lightgray')
)

base = base.add_params(
    rating_select
).encode(
    color=rating_color_condition
)

base