What are the best practices for setting fonts in PHPLOT for displaying special characters like the Euro symbol?

When displaying special characters like the Euro symbol in PHPLOT, it is important to set the appropriate font that supports these characters. One way to do this is by specifying a font that includes the special characters needed. This can be achieved by using the `TTF` font method in PHPLOT and selecting a font that supports the Euro symbol.

// Set the font for special characters like the Euro symbol
$graph->SetFont('TTF', 'path_to_font_file.ttf', font_size);