code: func yaml_emitter_analyze_anchor(emitter *yaml_emitter_t, anchor []byte, alias bool) bool {
  	if len(anchor) == 0 {
  		problem := "anchor value must not be empty"
  		if alias {
  			problem = "alias value must not be empty"
  		}
  		return yaml_emitter_set_emitter_error(emitter, problem)
  	}
  	for i := 0; i < len(anchor); i += width(anchor[i]) {
  		if !is_alpha(anchor, i) {
  			problem := "anchor value must contain alphanumerical characters only"
  			if alias {
  				problem = "alias value must contain alphanumerical characters only"
  			}
  			return yaml_emitter_set_emitter_error(emitter, problem)
  		}
  	}
  	emitter.anchor_data.anchor = anchor
  	emitter.anchor_data.alias = alias
  	return true
  }
docs: // Check if an anchor is valid.