filter.py

def filter_data(data):
    
    # Creating Dropdowns and buttons
    dropdown_currency = widgets.Dropdown(options=data.currency.unique(), description='Currency:')

    # Event handler for dropdowns 
    def dropdown_currency_eventhandler(change):
        common_filtering(data, change.new)
    
    #Call
    dropdown_currency.observe(dropdown_currency_eventhandler, names='value')

    #Layout box
    input_widgets = widgets.HBox([dropdown_currency])
    
    with filter_toggle_output:
        display(input_widgets)

def common_filtering(data, currency):
    
    common_filter = data[(data.currency == currency)]
        
    with data_output:
        display(common_filter)
    
    return common_filter