class_docstr: Find the length of the longest string in a column.
  
  Note: On Python 2.7 this function may miscalcuate the length of unicode
  strings that contain "wide characters". For details see this StackOverflow
  answer: https://stackoverflow.com/a/35462951
  
  :param column_name:
      The name of a column containing :class:`.Text` data.
code: def __init__(self, column_name):
      self._column_name = column_name
  
file_path: agate/agate/aggregations/max_length.py
imports: from decimal import Decimal
  from agate.aggregations.base import Aggregation
  from agate.data_types import Number, Text
  from agate.exceptions import DataTypeError
label_desc: Use image node_id 1 to create a new MaxLength object from inherited base classes: Aggregation with example: obj = MaxLength(column_name)