input: Write a function to generate n-grams of a given text with a specified window size. The function should return a Counter object that counts the occurrences of each n-gram. If the input text is empty, the function should return an empty Counter.
  
  def generate_ngrams(text, window_size):
      if not text:
          return Counter()
      text = text.lower().split(' ')
      ngrams = []
      for n in range(window_size, len(text)+1):
          for i in range(len(text)-n+1):
              ngrams.append(' '.join(text[i:i+n]))
      return Counter(ngrams)
  
  from collections import Counter
  
  assert generate_ngrams("The quick brown fox jumps over the lazy dog", 3)==Counter({'the quick brown': 3, 'quick brown fox': 2, 'over the lazy': 1, 'brown fox jumps': 1, 'fox jumps over': 1, 'the lazy dog': 1, 'jumps over the': 1, 'quick brown fox jumps': 1})
  assert generate_ngrams("The quick brown fox jumps", 2)==Counter({'the quick': 2, 'quick brown': 2, 'brown fox': 2, 'fox jumps': 2, 'the quick brown': 1, 'quick brown fox': 1, 'brown fox jumps': 1})
  assert generate_ngrams("", 3)==Counter()
  assert generate_ngrams("A", 1)==Counter({'a': 1})
  assert generate_ngrams("A A A", 1)==Counter({'a': 3})
output: def generate_ngrams(text, window_size):
      if not text:
          return Counter()
      text = text.lower().split(' ')
      ngrams = []
      for n in range(window_size, len(text)+1):
          for i in range(len(text)-n+1):
              ngrams.append(' '.join(text[i:i+n]))
      return Counter(ngrams)