old_contents: from parsl.app.errors import ParslError
  
  from typing import List
  
  
  class OptionalModuleMissing(ParslError):
      ''' Error raised when a required module is missing for a optional/extra component
      '''
  
      def __init__(self, module_names: List[str], reason: str):
          self.module_names = module_names
          self.reason = reason
  
      def __str__(self) -> str:
          return "The functionality requested requires missing optional modules {0}, because: {1}".format(
              self.module_names, self.reason
          )
  
new_contents: from parsl.app.errors import ParslError
  
  from typing import List
  
  
  class OptionalModuleMissing(ParslError):
      ''' Error raised when a required module is missing for a optional/extra component
      '''
  
      def __init__(self, module_names: List[str], reason: str):
          self.module_names = module_names
          self.reason = reason
  
      def __str__(self) -> str:
          return "The functionality requested requires optional modules {0} which could not be imported, because: {1}".format(
              self.module_names, self.reason
          )
  
subject: Rephrase optional module missing error (#2215)