Python: dictionary, keys and testing if a key exist

 get() methode for retrieval (no exception):

Using get() methode there is no need to handle any exception
return the value if exist, None if not.
ex:

dic = {'key1':'value1'}

dic.get('key1')

# out: 'value1'

dict.get('key2')

# out: None

====> you can specify a second argument, a value to be returned in case the key don't exist

ex: 

aValue = "i'm the replacement"

dic.get('key2',aValue)

 # out:  i'm the replacement

 Test if a key exist:

We use if [] in []:

  key = "key2"
  if key in dictionary:
        print("key exist")
  else:
        print("key Don't exist")