input: Write a python function to count the number of times each alphanumeric word is used in a given string.
  assert count_word_usage("Hello world! Hello universe.") == {'Hello': 2, 'world': 1, 'universe': 1}
  assert count_word_usage("123 456 123 789 123") == {'123': 3, '456': 1, '789': 1}
  assert count_word_usage("Python3 is great. Python3 is fun.") == {'Python3': 2, 'is': 2, 'great': 1, 'fun': 1}
output: def count_word_usage(s):
      import re
      from collections import Counter
      words = re.findall(r'\b\w+\b', s)
      return dict(Counter(words))