code: def letter_name(index):
      """
      Given a column index, assign a "letter" column name equivalent to
      Excel. For example, index ``4`` would return ``E``.
      Index ``30`` would return ``EE``.
      """
      letters = string.ascii_lowercase
      count = len(letters)
  
      return letters[index % count] * ((index // count) + 1)
  
imports: import math
  import string
  from collections import OrderedDict
  from collections.abc import Sequence
  from decimal import ROUND_CEILING, ROUND_FLOOR, Decimal, getcontext
  from functools import wraps
  from slugify import slugify
  from agate import config
  from agate.warns import warn_duplicate_column, warn_unnamed_column
label_desc: Use image node_id 6 for calling a global function with example usage: letter_name(index) and returns: unknown