text: from sqlalchemy.sql import expression
  from sqlalchemy.ext import compiler
  
  
  class group_concat_sqlite(expression.FunctionElement):
      name = "group_concat"
  
  
  @compiler.compiles(group_concat_sqlite, 'sqlite')
  def _group_concat_sqlite(element, compiler, **kw):
      if len(element.clauses) == 2:
          separator = element.clauses.clauses[1].value
      else:
          separator = ','
  
      return "GROUP_CONCAT({} , '{}')".format(
          compiler.process(element.clauses.clauses[0]),
          separator,
      )
  