input: Write a python function to count the occurrences of a specific word in a given string.
  assert count_occurences('The quick brown fox', 'The') == 1
  assert count_occurences('The quick brown fox jumped over the lazy dog', 'the') == 1
  assert count_occurences('The quick brown fox jumped over the lazy dog', 'fox') == 1
  assert count_occurences('The quick brown fox jumped over the quick brown dog', 'quick') == 2
output: def count_occurences(s: str, word: str) -> int:
      return s.split().count(word)