class_docstr: Calculate the sum of a column.
  
  :param column_name:
      The name of a column containing :class:`.Number` data.
code: def __init__(self, column_name):
      self._column_name = column_name
  
file_path: agate/agate/aggregations/sum.py
imports: import datetime
  from agate.aggregations.base import Aggregation
  from agate.data_types import Number, TimeDelta
  from agate.exceptions import DataTypeError
label_desc: Use image node_id 1 to create a new Sum object from inherited base classes: Aggregation with example: obj = Sum(column_name)