Get value not none

[Clives]

Apologies I forgot to add the ipywidgets

from ipywidgets import interact, widgets
from IPython.display import display

import urllib
import urllib.parse
from urllib.parse import urlparse
import urllib.request
from   urllib.request import urlopen
 
def get_method_dropdown():
    methods = ['DEV', 'TEMP', 'PROD']
    method_widget = widgets.Dropdown(
        options=methods,
        value=methods[0],
        description='Env:'
    )
    display(method_widget)
 
#    methods_widget.on_trait_change(filter_istd_qc_by_method,'value')
 
    return method_widget 
         
d = widgets.Dropdown(
        options=['DEV', 'TEMP', 'PROD'], value='TEMP'
)
display(d)
#print(d.value)
 
 
output2 = widgets.Output()
#display(d, output2)
 
def get_value(change):
    print(change['new'])
    #print(select_variable.value)
    #clear_output()
 
source_ = d.observe(get_value, names='value')  ### get_value, names='value'
 
#print(source_)
 
if source_ == 'DEV':
    print("DEV = Output")
elif source_ == 'TEMP':
    print("TEMP = Output")