docs: def check_syntax(string):
      """ Check syntax of a string of PostgreSQL-dialect SQL """
      args = ["ecpg", "-o", "-", "-"]
  
      with open(os.devnull, "w") as devnull:
          try:
              proc = subprocess.Popen(args, shell=False,
                                      stdout=devnull,
                                      stdin=subprocess.PIPE,
                                      stderr=subprocess.PIPE,
                                      universal_newlines=True)
              _, err = proc.communicate(string)
          except OSError:
              msg = "Unable to execute 'ecpg', you likely need to install it.'"
              raise OSError(msg)
          if proc.returncode == 0:
              return (True, "")
          else:
              return (False, parse_error(err))