person_3 = {
    "fname": "Joseph", 
    "dob": "12/07/2011", 
    "city": "Dallas"
}

d1 = {'a': 12, 'b':20}

k = d1.keys()

for item in k:
	print(item)

d1['c'] = 'hello'

for item in k:
	print(item)
	
da = {'a': 2, 'the': 4} # count the occurences of word.

# new count: hello appears 3 times.
da['hello'] = 3

# hello appears one more times
da['hello'] += 1  # da['hello'] = da['hello'] + 1


db = {'bird': 2, 'monkey':4}  # some other sources

# merging counting in db to da
da.update(db)

da.update({'monkey': 25, 'tiger': 7})


dc = {'a': 10, 'e': 'hey'}

len(dc.keys())
dc['f'] = [1,3,5,6]

dc['f'] = "I like a string now."

dc['f'] = {'s1': [1,3,5,6], 100: {'x': 1, 'y':2}}