code: def where_exists(self, query, boolean="and", negate=False):
          
          if isinstance(query, Builder):
              query = query.get_query()
  
          self.get_query().where_exists(query, boolean, negate)
  
          return self
docs: Add an exists clause to the query.
  
          :param query: The exists query
          :type query: Builder or QueryBuilder
  
          :type boolean: str
  
          :type negate: bool
  
          :rtype: Builder