input: Write a python function to count the occurrence of a specific word in a given string.
  assert count_word_occurrence("The quick brown fox jumps over the lazy dog", "fox") == 1
  assert count_word_occurrence("hello hello hello", "hello") == 3
  assert count_word_occurrence("test the function with test cases", "test") == 2
output: def count_word_occurrence(string, word):
      return string.split().count(word)