docstr: Return the underline thickness as float
docstr_tok: ["Return","the","underline","thickness","as","float"]
code: def get_underline_thickness(self):
      "Return the underline thickness as float"
      return self._header[b"UnderlineThickness"]
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  from six.moves import map
  import sys
  import re
  from ._mathtext_data import uni2type1
label_desc: Use image node_id 20 for calling the AFM obj's underlying member method code with example usage: obj.get_underline_thickness() and returns: self