class_docstr: Lexer for `YAML <http://yaml.org/>`_, a human-friendly data serialization
  language.
  
  .. versionadded:: 0.11
docstr: Set an explicit indentation level for a block scalar.
docstr_tok: ["Set","an","explicit","indentation","level","for","a","block","scalar","."]
code: def set_block_scalar_indent(token_class):
      """Set an explicit indentation level for a block scalar."""
  
      def callback(lexer, match, context):
          text = match.group()
          context.block_scalar_indent = None
          if not text:
              return
          increment = match.group(1)
          if increment:
              current_indent = max(context.indent, 0)
              increment = int(increment)
              context.block_scalar_indent = current_indent + increment
          if text:
              yield match.start(), token_class, text
              context.pos = match.end()
  
      return callback
  
imports: import re
  from pygments.lexer import RegexLexer, ExtendedRegexLexer, LexerContext, include, bygroups, inherit
  from pygments.token import Text, Comment, Keyword, Name, String, Number, Punctuation, Literal, Error
label_desc: Use image node_id 5 for calling the YamlLexer obj's underlying member method code with example usage: obj.set_block_scalar_indent(token_class) and returns: callback