Finally a clean way to update dictionaries in python if you're unsure all keys exist

update_dict.py

your_dict = {}
for i in some_iterator:
    your_dict[i] = new_value if i not in your_dict else your_dict[i]+new_value
  
'''a version with the new value coming from a new dict'''
your_dict = {}
for i in some_iterator:
    your_dict[i] = new_values[i] if i not in your_dict else your_dict[i]+new_values[i]
  
'''a kinda dumb example; letter frequencies'''
letter_counts, letters = {}, ['a','b','a','b','a','c']
for l in letters:
    letter_counts[l] = 1 if l not in letter_counts else letter_counts[l]+1
'''returns: {'a': 3, 'b': 2, 'c': 1}'''