class_docstr: Aggregations create a new value by summarizing a :class:`.Column`.
  
  Aggregations are applied with :meth:`.Table.aggregate` and
  :meth:`.TableSet.aggregate`.
  
  When creating a custom aggregation, ensure that the values returned by
  :meth:`.Aggregation.run` are of the type specified by
  :meth:`.Aggregation.get_aggregate_data_type`. This can be ensured by using
  the :meth:`.DataType.cast` method. See :class:`.Summary` for an example.
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docstr: String representation of this column. May be used as a column name in
  generated tables.
docstr_tok: ["String","representation","of","this","column",".","May","be","used","as","a","column","name","in","generated","tables","."]
code: def __str__(self):
      """
      String representation of this column. May be used as a column name in
      generated tables.
      """
      return self.__class__.__name__
  
imports: from agate.exceptions import UnsupportedAggregationError
label_desc: Use image node_id 1 for calling the Aggregation obj's underlying member method code with example usage: obj.__str__() and returns: self