input: from typing import List, Dict
  
  
  def scrape_planets_data(url: str) -> List[Dict[str, str]]:
      """Given a URL, scrape the table containing information about planets and extract 
      each planet's name, mass, and distance from the sun. 
      
      >>> scrape_planets_data('https://en.wikipedia.org/wiki/List_of_gravitationally_rounded_objects_of_the_Solar_System')
      [{'name': 'Mercury', 'mass': '0.0553 (5.53×10−2)', 'distance_from_sun': '0.4'} ... ]
      """
output:     
      import requests
      from bs4 import BeautifulSoup
  
      response = requests.get(url)
      soup = BeautifulSoup(response.content, 'html.parser')
      table = soup.find('table', {'class': 'wikitable'})
      
      planets_data = []
      rows = table.find_all('tr')
      
      for row in rows[1:]:
          cols = row.find_all('td')
          if len(cols) >= 4:
              name = cols[0].get_text(strip=True)
              mass = cols[1].get_text(strip=True)
              distance_from_sun = cols[2].get_text(strip=True)
              planets_data.append({'name': name, 'mass': mass, 'distance_from_sun': distance_from_sun})
      
      return planets_data
  