input: Write a python function to scrape job postings from a given list of job boards and extract the job title, company, and location.
  assert scrape_job_postings(['Monster.com'])[0]['title'] != ''
  assert scrape_job_postings(['LinkedIn.com'])[0]['company'] != ''
  assert scrape_job_postings(['Stack Overflow'])[0]['location'] != ''
output: def scrape_job_postings(job_boards):
      import requests
      from bs4 import BeautifulSoup
      
      job_postings = []
  
      for board in job_boards:
          if 'Monster.com' in board:
              url = 'https://www.monster.com/jobs/search'
              response = requests.get(url)
              soup = BeautifulSoup(response.content, 'html.parser')
              jobs = soup.find_all('section', class_='card-content')
              for job in jobs:
                  title = job.find('h2', class_='title').text.strip()
                  company = job.find('div', class_='company').text.strip()
                  location = job.find('div', class_='location').text.strip()
                  job_postings.append({'title': title, 'company': company, 'location': location})
  
          elif 'LinkedIn.com' in board:
              url = 'https://www.linkedin.com/jobs/search'
              response = requests.get(url)
              soup = BeautifulSoup(response.content, 'html.parser')
              jobs = soup.find_all('div', class_='result-card__contents')
              for job in jobs:
                  title = job.find('h3', class_='result-card__title').text.strip()
                  company = job.find('h4', class_='result-card__subtitle').text.strip()
                  location = job.find('span', class_='job-result-card__location').text.strip()
                  job_postings.append({'title': title, 'company': company, 'location': location})
  
          elif 'Stack Overflow' in board:
              url = 'https://stackoverflow.com/jobs'
              response = requests.get(url)
              soup = BeautifulSoup(response.content, 'html.parser')
              jobs = soup.find_all('div', class_='-job')
              for job in jobs:
                  title = job.find('a', class_='s-link').text.strip()
                  company = job.find('h3', class_='fc-black-700').find_all('span')[0].text.strip()
                  location = job.find('h3', class_='fc-black-700').find_all('span')[1].text.strip()
                  job_postings.append({'title': title, 'company': company, 'location': location})
      
      return job_postings