how to make each key-value of a dictionary print on a new line?

If you really don't want to import pprint but want it to "look like" a dictionary, you could do:

print("{" + "\n".join("{!r}: {!r},".format(k, v) for k, v in d.items()) + "}")

You may be looking for pprint, the pretty printer standard library. For example:

import pprint
pprint.pprint({'avglen': 4.419354838709677, 
               'count:': 93,
               'mosts:': 'your',
               'longs:': ['stretched'],
               'shorts:': ['i', 'a'],})

outputs

{'avglen': 4.419354838709677,
 'count:': 93,
 'longs:': ['stretched'],
 'mosts:': 'your',
 'shorts:': ['i', 'a']}