input: Write a python function to fetch and parse weather forecast data from a given URL and extract the daily forecast details using lxml. 
  assert fetch_weather_forecast('http://www.example.com/weather') == [{'day': 'Monday', 'high_temp': '25', 'low_temp': '15', 'weather': 'Sunny'}, {'day': 'Tuesday', 'high_temp': '22', 'low_temp': '14', 'weather': 'Cloudy'}]
  assert fetch_weather_forecast('http://www.example.com/weather') == [{'day': 'Wednesday', 'high_temp': '20', 'low_temp': '10', 'weather': 'Rainy'}, {'day': 'Thursday', 'high_temp': '18', 'low_temp': '8', 'weather': 'Windy'}]
output: import requests
  from lxml import html
  
  def fetch_weather_forecast(url):
      response = requests.get(url)
      tree = html.fromstring(response.content)
      
      forecasts = []
      days = tree.xpath('//div[@class="day"]/text()')
      high_temps = tree.xpath('//div[@class="high_temp"]/text()')
      low_temps = tree.xpath('//div[@class="low_temp"]/text()')
      weathers = tree.xpath('//div[@class="weather"]/text()')
      
      for day, high_temp, low_temp, weather in zip(days, high_temps, low_temps, weathers):
          forecasts.append({
              'day': day.strip(),
              'high_temp': high_temp.strip(),
              'low_temp': low_temp.strip(),
              'weather': weather.strip()
          })
      
      return forecasts