class RuboCop::AST::StrNode

its methods available to all ‘str` nodes within RuboCop.
in place of a plain node when the builder constructs the AST, making
A node extension for `str`, `dstr`, and `xstr` nodes. This will be used

def character_literal? 

def character_literal?
  loc.respond_to?(:begin) && loc.begin && loc.begin.is?('?')
end

def heredoc? 

def heredoc?
  loc.is_a?(Parser::Source::Map::Heredoc)
end