code: def __render_tag(info, state):
      
      new_contexts, context_match = get_tag_context(info['tag_key'], state)
      replacement = ''
  
      if context_match or context_match == 0:
          replacement = context_match
      elif info['tag_key'] == '.':
          replacement = state.context()
      else:
          replacement = ''
  
      # Call all callables / methods / lambdas / functions
      if replacement and callable(replacement):
          replacement = make_unicode(replacement())
  
          state.push_tags(state.default_tags)
          replacement = __render(template=replacement, state=state)
          state.pop_tags()
  
      for i in xrange(new_contexts): state.context.pop()
  
      if state.escape():
          return html_escape(replacement)
      return replacement
docs: Render an individual tag by making the appropriate replacement within
      the current context (if any).