class_docstr: Calculate the mode 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/mode.py
imports: from collections import defaultdict
  from agate.aggregations.base import Aggregation
  from agate.aggregations.has_nulls import HasNulls
  from agate.data_types import Number
  from agate.exceptions import DataTypeError
  from agate.warns import warn_null_calculation
label_desc: Use image node_id 1 to create a new Mode object from inherited base classes: Aggregation with example: obj = Mode(column_name)