input: Write a python function to send an email using SMTP.
  assert send_email("sender@example.com", ["recipient@example.com"], "Test Subject", "Test Body") == None
  assert send_email("admin@example.com", ["user1@example.com", "user2@example.com"], "Meeting Reminder", "Don't forget our meeting at 10 AM.") == None
output: def send_email(sender_email, recipient_emails, subject, body):
      import smtplib
      from email.mime.text import MIMEText
      from email.mime.multipart import MIMEMultipart
  
      # Create the email headers
      msg = MIMEMultipart()
      msg['From'] = sender_email
      msg['To'] = ", ".join(recipient_emails)
      msg['Subject'] = subject
  
      # Attach the email body
      msg.attach(MIMEText(body, 'plain'))
  
      try:
          # Set up the SMTP server
          with smtplib.SMTP('smtp.example.com', 587) as server:
              server.starttls()  # Secure the connection
              server.login('your_username', 'your_password')
              server.sendmail(sender_email, recipient_emails, msg.as_string())
      except Exception as e:
          print(f"Failed to send email: {e}")