Check if Key Exists :

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
if "model" in thisdict:
  print("Yes, 'model' is one of the keys in the thisdict dictionary")

Output :

Yes, 'model' is one of the keys in the thisdict dictionary

Change Dictionary Value :

thisdict["year"] = 2018
print(thisdict)

Output :

{'brand': 'Ford', 'model': 'Mustang', 'year': 2018}

Update Dictionary Value using update() :

thisdict.update({"year": 2020})
print(thisdict)

Output :

{'brand': 'Ford', 'model': 'Mustang', 'year': 2020}

Add New Item to Dictionary :

thisdict["color"] = "red"
print(thisdict)

Output :

{'brand': 'Ford', 'model': 'Mustang', 'year': 2020, 'color': 'red'}

Add Item using update() :

thisdict.update({"engine": "V8"})
print(thisdict)

Output :

{'brand': 'Ford', 'model': 'Mustang', 'year': 2020, 'color': 'red', 'engine': 'V8'}