code: protected function convert_value_to_string( $value ) {
  
  		if ( $this->is_resource( $value ) ) {
  
  			$type = get_resource_type( $value );
  
  			return "(Resource:$type)";
  		}
  
  		if ( is_object( $value ) ) {
  
  			if ( $value instanceof \Exception || $value instanceof \Throwable ) {
  				return '(' . get_class( $value ) . "#{$value->getCode()}:{$value->getMessage()})";
  			} elseif ( $value instanceof \DateTime || ( interface_exists( '\DateTimeInterface' ) && $value instanceof \DateTimeInterface ) ) {
  				return $value->format( \DateTime::ATOM );
  			} elseif ( method_exists( $value, '__toString' ) ) {
  				return (string) $value;
  			} else {
  
  				$class = get_class( $value );
  
  				return "($class)";
  			}
  		}
  
  		if ( is_array( $value ) ) {
  			return '(Array)';
  		}
  
  		if ( is_scalar( $value ) ) {
  			return $value;
  		}
  
  		if ( $value === null ) {
  			return '(Null)';
  		}
  
  		return '(Invalid)';
  	}
docs: Converts a value of unknown type to a string.
  
  @param mixed $value
  
  @return string