code: def default(fields=None, count=5):
      
      projection = Sampling._create_projection(fields)
      return lambda sql: 'SELECT %s FROM (%s) LIMIT %d' % (projection, sql, count)
docs: Provides a simple default sampling strategy which limits the result set by a count.
  
      Args:
        fields: an optional list of field names to retrieve.
        count: optional number of rows to limit the sampled results to.
      Returns:
        A sampling function that can be applied to get a random sampling.