_extract_callstack

# File activesupport/lib/active_support/deprecation/reporting.rb, line 92
        def _extract_callstack(callstack)
          warn "Please pass `caller_locations` to the deprecation API" if $VERBOSE
          offending_line = callstack.find { |line| !ignored_callstack(line) } || callstack.first

          if offending_line
            if md = offending_line.match(/^(.+?):(\d+)(?::in `(.*?)')?/)
              md.captures
            else
              offending_line
            end
          end
        end