code: def render(self, style_attr, value):
          
          if not value.strip():
              # We've got an empty string.  Don't bother adding any
              # codes.
              return value
          return six.text_type(getattr(self.term, style_attr)) + value
docs: Prepend terminal code for `key` to `value`.
  
          Parameters
          ----------
          style_attr : str
              A style attribute (e.g., "bold" or "blue").
          value : str
              The value to render.
  
          Returns
          -------
          The code for `key` (e.g., "\x1b[1m" for bold) plus the
          original value.