ELEMENT = </?[     ]*[a-zA-Z0-9]*
WHITESPACE = [  ]*
ATTRIBUTE = [a-zA-Z0-9]*[   ]*=
ATTRIBUTE_CONTENT_DOUBLE_QUOTES = [ ]*"[a-zA-Z0-9    '!@#$%^&*()_-+={}|\;:/?.,`~]*"
ATTRIBUTE_CONTENT_SINGLE_QUOTES = [ ]*'[a-zA-Z0-9    !"@#$%^&*()_-+={}|\;:/?.,`~]*'
BRACKET = [<>]