code: def sampling_query(sql, fields=None, count=5, sampling=None):
      
      if sampling is None:
        sampling = Sampling.default(count=count, fields=fields)
      return sampling(sql)
docs: Returns a sampling query for the SQL object.
  
      Args:
        sql: the SQL object to sample
        fields: an optional list of field names to retrieve.
        count: an optional count of rows to retrieve which is used if a specific
            sampling is not specified.
        sampling: an optional sampling strategy to apply to the table.
      Returns:
        A SQL query string for sampling the input sql.