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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def have_font(font_name):
 """Return True if the given font name is registered as one of our externally loadable fonts. If `font_name` is not found, it will try to look it up as an alias and report if that is found. """

    if font_name in font_dir:
        return True

    # try it as an alias
    font_name = resolve_alias(font_name, font_name)
    return font_name in font_dir