isIsoValid
Checks the validity of a language tag
Return
True/false if the provided tag is ISO valid for languages
Example - 'fr-FR' is a language tag and is valid
Example - 'sw320dp' is a screen dimension tag and is not valid
Checks the validity of a language tag
True/false if the provided tag is ISO valid for languages
Example - 'fr-FR' is a language tag and is valid
Example - 'sw320dp' is a screen dimension tag and is not valid