class_docstr: For `Notmuch <https://notmuchmail.org/>`_ email text format.
  
  .. versionadded:: 2.5
  
  Additional options accepted:
  
  `body_lexer`
      If given, highlight the contents of the message body with the specified
      lexer, else guess it according to the body content (default: ``None``).
code: def analyse_text(text):
      return 1.0 if text.startswith("\fmessage{") else 0.0
  
imports: import re
  from pygments.lexers import guess_lexer, get_lexer_by_name
  from pygments.lexer import RegexLexer, bygroups, default, do_insertions
  from pygments.token import Text, Comment, Operator, Keyword, Name, String, Number, Generic, Literal, Punctuation
  from pygments.util import ClassNotFound
label_desc: Use image node_id 2 for calling the NotmuchLexer obj's underlying member method code with example usage: obj.analyse_text(text) and returns: unknown