old_contents: import os
  from enum import Enum
  from typing import Optional
  from pydantic import BaseSettings, validator
  
  
  class CacheType(str, Enum):
      NO_CACHE = 'no_cache'
      FILE_CACHE = 'file_cache'
      MONGO_CACHE = 'mongo_cache'
  
  
  class Settings(BaseSettings):
      mongodb_uri: Optional[str] = None
      mapi_key: str = ''
      rxn_files: str = os.path.join(
          os.path.dirname(os.path.abspath(__file__)),
          'files'
      )
  
      cache_type: CacheType = CacheType.FILE_CACHE
      use_mapi_db: bool = False
  
      @validator('cache_type')
      def check_cache_type(cls, v, values):
          if v == CacheType.MONGO_CACHE:
              if not values.get('mongodb_uri'):
                  raise ValueError('MONGODB_URI must be provided when using mongo cache.')
          return v
  
      @validator('use_mapi_db')
      def check_mongo_uri_exists_for_mapi_db(cls, v, values):
          if v:
              if not values.get('mongodb_uri'):
                  raise ValueError('MONGODB_URI must be provided when using mapi DB.')
          return v
  
      class Config:
          allow_mutation = False
  
  
  
  settings = Settings()
  
new_contents: import os
  from enum import Enum
  from typing import Optional
  from pydantic import BaseSettings, validator
  
  
  class CacheType(str, Enum):
      NO_CACHE = 'no_cache'
      FILE_CACHE = 'file_cache'
      MONGO_CACHE = 'mongo_cache'
  
  
  class Settings(BaseSettings):
      mongodb_uri: Optional[str] = None
      mapi_key: str = ''
      rxn_files: str = os.path.join(
          os.path.dirname(os.path.abspath(__file__)),
          'files'
      )
  
      cache_type: CacheType = CacheType.FILE_CACHE
      use_mapi_db: bool = False
  
      @validator('cache_type')
      def check_cache_type(cls, v, values):
          if v == CacheType.MONGO_CACHE:
              if not values.get('mongodb_uri'):
                  raise ValueError('MONGODB_URI must be provided when using mongo cache.')
          return v
  
      @validator('use_mapi_db')
      def check_mongo_uri_exists_for_mapi_db(cls, v, values):
          if v:
              if not values.get('mongodb_uri'):
                  raise ValueError('MONGODB_URI must be provided when using mapi DB.')
          return v
  
      class Config:
          allow_mutation = False
  
  
  settings = Settings()
  
subject: fix lint