input: Write a function to generate n-grams of a given text with a specified window size. The function should return a Counter object containing the frequency of each n-gram. If the window size is larger than the length of the text, the function should return an empty Counter.
  assert generate_ngrams("The quick brown fox jumps over the lazy dog", 3) == Counter({'the quick brown': 1, 'quick brown fox': 1, 'brown fox jumps': 1, 'fox jumps over': 1, 'jumps over the': 1, 'over the lazy': 1, 'the lazy dog': 1})
  assert generate_ngrams("The quick brown fox jumps over the lazy dog", 4) == Counter({'the quick brown fox': 1, 'quick brown fox jumps': 1, 'brown fox jumps over': 1, 'fox jumps over the': 1, 'jumps over the lazy': 1, 'over the lazy dog': 1})
  assert generate_ngrams("The quick brown fox jumps over the lazy dog", 10) == Counter()
  assert generate_ngrams("", 3) == Counter()
output: from collections import Counter
  
  def generate_ngrams(text, window_size):
      if window_size > len(text.split()):
          return Counter()
      words = text.split()
      ngrams = [' '.join(words[i:i+window_size]) for i in range(len(words) - window_size + 1)]
      return Counter(ngrams)