input: Write a python function to fetch webpage content based on action using BeautifulSoup and requests.
  assert fetch_webpage_content("producto.info", {"producto": "hogar"}) != "No encontrado"
  assert fetch_webpage_content("planes.salud", {}) != " "
  assert fetch_webpage_content("info.especialistas", {"plan-salud": "salud", "ciudad": "bogota", "especialidad": "cardiologia"}) != " "
output: def fetch_webpage_content(action, params):
      import requests
      from bs4 import BeautifulSoup
  
      base_url = "http://example.com/"
      url = base_url + action
      response = requests.get(url, params=params)
  
      if response.status_code != 200:
          return "No encontrado"
  
      soup = BeautifulSoup(response.content, 'html.parser')
      content = soup.get_text(strip=True)
  
      if not content:
          return " "
  
      return content