code: func (builder *SSMLTextBuilder) AppendEmphasis(text, level string) *SSMLTextBuilder {
  
  	builder.buffer.WriteString(fmt.Sprintf("<emphasis level=\"%s\">%s</emphasis>", level, text))
  
  	return builder
  }
docs: // AppendEmphasis will include a set of text to be spoken with the specific level of emphasis.
  // Refer to the SSML reference for available emphasis level values.