code: def list_files(bucket, profile_name=None):
      
      session = boto3.Session(profile_name=profile_name)
      conn = session.client('s3')
      keys = []
      ret = conn.list_objects(Bucket=bucket)
      print(ret)
      if 'Contents' not in ret:
          return []
      # Make this a generator in future and use the marker:
      # https://boto3.readthedocs.io/en/latest/reference/services/
      #     s3.html#S3.Client.list_objects
      for key in conn.list_objects(Bucket=bucket)['Contents']:
          keys.append('s3://' + bucket + '/' + key['Key'])
      return keys
docs: List up to 1000 files in a bucket.
  
      Parameters
      ----------
      bucket : str
      profile_name : str, optional
          AWS profile
  
      Returns
      -------
      s3_paths : List[str]