text: from libraries.model import fill_region, fill_iam, fill_ec2, fill_network
  from libraries.model import fill_s3, fill_rds, fill_cloudtrail
  
  def scan(account, region_list, services, session):
      """
      scan load an account node children ressources using the session parameter to
      query AWS API on the aws services selected in the services parameter
  
      Parameters
      ----------
      account : node (object define in Model.py)
          Currently the base element of the model
      region_list : [str]
          list of the aws region that will be scanned
      services : {service_name:bool}
          dictionary that references the services to be scanned
      session
          a boto3 session allowing to query AWS APIs
      """
      # Loads the s3 resources to the account node children
      if services.get('s3'):
          fill_s3(session=session, account=account)
      # Loads the iam resources to the account node children
      if services.get('iam'):
          fill_iam(session=session, account=account)
  
      # Checking whether the region_node will be necessary
      region_based_services = (services.get('cloudtrail')
                               or services.get('network')
                               or services.get('ec2')
                               or services.get('rds'))
  
      if region_based_services:
          # Using the parameter region_list to create region nodes
          # to host the resources of the region based services
          fill_region(region_list=region_list, account=account)
          region_node_list = account.get_child_list('Region')
          if services.get('cloudtrail'):
              for region_node in region_node_list:
                  fill_cloudtrail(session, region_node)
          if services.get('network'):
              for region_node in region_node_list:
                  fill_network(session, region_node)
          if services.get('ec2'):
              for region_node in region_node_list:
                  fill_ec2(session, region_node)
          if services.get('rds'):
              for region_node in region_node_list:
                  fill_rds(session, region_node)
  