class_docstr: Show precision significant digit of float
class_docstr_tok: ["Show","precision","significant","digit","of","float"]
code: def __call__(self, val):
      if val is None:
          return ""
      return self.format % 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 2 for calling the Significant obj's underlying member method code with example usage: obj.__call__(val) and returns: unknown, str