Gives a list of valid Language Codes for Google Fonts, or validates that the language codes given are valid.
google_language_codes(language_codes = c("latin", "latin-ext", "sinhala",
"greek", "hebrew", "vietnamese", "cyrillic", "cyrillic-ext", "devanagari",
"arabic", "khmer", "tamil", "greek-ext", "thai", "bengali", "gujarati",
"oriya", "malayalam", "gurmukhi", "kannada", "telugu", "myanmar"))
Vector of potential Google language codes