input: Write a function to connect to and query data from three different databases (MySQL, MongoDB, and PostgreSQL) using their respective libraries, and then display the queried data on a web page. The function should also close the connections to the databases after querying.
  
  def render_page(request):
      import pymysql
      from pymongo import MongoClient
      import psycopg2
  
      # connect to MySQL
      connection_mysql = pymysql.connect(host='localhost', user='root', password='password', database='db_name')
      # connect to MongoDB
      client = MongoClient('mongodb://localhost:27017')
      # connect to PostgreSQL
      connection_postgresql = psycopg2.connect(host='localhost', user='postgres', password='password', dbname='db_name')
  
      # define a query for each database
      query_mysql = 'SELECT * FROM table_name'
      query_mongodb = {'name': 'John Doe'}
      query_postgresql =  'SELECT * FROM table_name WHERE age > 18'
  
      # execute the query and fetch the results
      with connection_mysql.cursor() as cursor:
          cursor.execute(query_mysql)
          result_mysql = cursor.fetchall()
      result_mongodb = list(client.db_name.collection_name.find(query_mongodb))
      with connection_postgresql.cursor() as cursor:
          cursor.execute(query_postgresql)
          result_postgresql = cursor.fetchall()
  
      # close the connections
      connection_mysql.close()
      client.close() 
      connection_postgresql.close()
  
      return render(request, 'template.html', {
          'data_mysql': result_mysql, 
          'data_mongodb': result_mongodb,
          'data_postgresql': result_postgresql
      })
  
  assert render_page('request')  # Expected to render webpage with data from three databases
  assert 'data_mysql' in render_page('request')  # Expected to contain MySQL data in the rendered webpage
  assert 'data_mongodb' in render_page('request')  # Expected to contain MongoDB data in the rendered webpage
  assert 'data_postgresql' in render_page('request')  # Expected to contain PostgreSQL data in the rendered webpage
  assert connection_mysql.closed  # Expected MySQL connection to be closed after querying
  assert client.closed  # Expected MongoDB connection to be closed after querying
  assert connection_postgresql.closed  # Expected PostgreSQL connection to be closed after querying
output: def render_page(request):
      import pymysql
      from pymongo import MongoClient
      import psycopg2
  
      connection_mysql = pymysql.connect(host='localhost', user='root', password='password', database='db_name')
      client = MongoClient('mongodb://localhost:27017')
      connection_postgresql = psycopg2.connect(host='localhost', user='postgres', password='password', dbname='db_name')
  
      query_mysql = 'SELECT * FROM table_name'
      query_mongodb = {'name': 'John Doe'}
      query_postgresql =  'SELECT * FROM table_name WHERE age > 18'
  
      with connection_mysql.cursor() as cursor:
          cursor.execute(query_mysql)
          result_mysql = cursor.fetchall()
      result_mongodb = list(client.db_name.collection_name.find(query_mongodb))
      with connection_postgresql.cursor() as cursor:
          cursor.execute(query_postgresql)
          result_postgresql = cursor.fetchall()
  
      connection_mysql.close()
      client.close() 
      connection_postgresql.close()
  
      return render(request, 'template.html', {
          'data_mysql': result_mysql, 
          'data_mongodb': result_mongodb,
          'data_postgresql': result_postgresql
      })