input: Write a function to search for a specific word in a text file.
  assert search_for_word("example.txt", "hello") == True
  assert search_for_word("example.txt", "world") == False
  assert search_for_word("example.txt", "Python") == True
output: def search_for_word(filename, word):
      with open(filename, 'r') as file:
          for line in file:
              if word in line:
                  return True
      return False