code: def from_app(cls, app, environ, buffered=False):
          
          return cls(*_run_wsgi_app(app, environ, buffered))
docs: Create a new response object from an application output.  This
          works best if you pass it an application that returns a generator all
          the time.  Sometimes applications may use the `write()` callable
          returned by the `start_response` function.  This tries to resolve such
          edge cases automatically.  But if you don't get the expected output
          you should set `buffered` to `True` which enforces buffering.
  
          :param app: the WSGI application to execute.
          :param environ: the WSGI environment to execute against.
          :param buffered: set to `True` to enforce buffering.
          :return: a response object.