input: Write a function to generate n-grams of the given text with a specified window size. The function should return a Counter object with the n-grams and their counts. If no n-grams can be generated due to insufficient text, the function should return an empty Counter.
  
  from collections import Counter
  
  def generate_ngrams(text, window_size):
      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)
  
  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("Hello World", 2) == Counter({'hello world': 2})
  assert generate_ngrams("Short", 3) == Counter()
  assert generate_ngrams("", 3) == Counter()
  assert generate_ngrams("One two three four", 1) == Counter({'one': 1, 'two': 1, 'three': 1, 'four': 1})
output: def generate_ngrams(text, window_size):
      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)