class_docstr: Try to guess best format from type
class_docstr_tok: ["Try","to","guess","best","format","from","type"]
code: def __call__(self, val):
      if val is None:
          return ""
      if isinstance(val, (int, float)):
          return Significant.__call__(self, val)
      if isinstance(val, (date, time, datetime)):
          return IsoDateTime.__call__(self, val)
      return Raw.__call__(self, val)
  
imports: from __future__ import division
  from datetime import date, datetime, time
  from math import floor, log
  from pygal.util import float_format
label_desc: Use image node_id 1 for calling the Default obj's underlying member method code with example usage: obj.__call__(val) and returns: Raw, str, Significant, IsoDateTime