name_to_age = {'Alice': 35, 'Dharmik': 42, 'Kara': 21, 'David': 56, 'Venkat': 7}
# note that we don't necessarily print in order
print("How do you print the entire dictionary? ", name_to_age)

# name_to_age[1]

print("How do you get the age of Alice? Alice is:", name_to_age['Alice'])

#print("Helen is:", name_to_age['Helen'])
print("Is Helen in the dictionary?" , 'Helen' in name_to_age)

# another approach
age = name_to_age.get('Ann')
print("How do you get the age of Ann (a stranger)", age)
age = name_to_age.get('Helen')
print("How do you get the age of Helen (a stranger)", age)
# we can specify a 2nd parameter for get, what to return if the first parameter
# isn't in the dictionary
age = name_to_age.get('Helen', 50)
print("Since I don't know Helen's age, I guess it is ", age)

# dictionaries are mutable
name_to_age['Dharmik'] += 1
print("Say happy birthday to Dharmik! ", name_to_age)

# can we get rid of an entry?
name_to_age['Kara'] = None
print("How do I delete Kara from the dictionary? ", name_to_age)

# we can use the del operator
del name_to_age['Kara']
print("Finally we can delete Kara", name_to_age)

# loop over keys in a list
for next_name in name_to_age:
    # once again, note that
    # we're not going in any specific order
    print(next_name, " is ", name_to_age[next_name], " years old")

# keys must be immutable types
my_dict = {}
# so this will work
my_dict['x'] = ['a', 'b', 'c']
# but this will crash
# my_dict[['a', 'b', 'c']] = 'x'