code: def _get_pwd_context(self, app: FlaskUnchained) -> CryptContext:
          
          pw_hash = app.config.SECURITY_PASSWORD_HASH
          schemes = app.config.SECURITY_PASSWORD_SCHEMES
          if pw_hash not in schemes:
              allowed = (', '.join(schemes[:-1]) + ' and ' + schemes[-1])
              raise ValueError(f'Invalid password hashing scheme {pw_hash}. '
                               f'Allowed values are {allowed}.')
          return CryptContext(schemes=schemes, default=pw_hash,
                              deprecated=app.config.SECURITY_DEPRECATED_PASSWORD_SCHEMES)
docs: Get the password hashing context.