code: func (b *Bmatrix) containsAttachment(content map[string]interface{}) bool {
  	// Skip empty messages
  	if content["msgtype"] == nil {
  		return false
  	}
  
  	// Only allow image,video or file msgtypes
  	if !(content["msgtype"].(string) == "m.image" ||
  		content["msgtype"].(string) == "m.video" ||
  		content["msgtype"].(string) == "m.file") {
  		return false
  	}
  	return true
  }
docs: // skipMessages returns true if this message should not be handled