import re
stuff = ["$x$y0123", "$", "", " \t", "$x @hi"]
p1 = re.compile(r'(?:\$[A-Z_]\w*|\s)*$', re.IGNORECASE)
p2 = re.compile(r'\$[A-Z_]\w*|\s+', re.IGNORECASE)
for thing in stuff:
if p1.match(thing):
print(p2.findall(thing))
aW1wb3J0IHJlCnN0dWZmID0gWyIkeCR5MDEyMyIsICIkIiwgIiIsICIgIFx0IiwgIiR4ICAgICAgQGhpIl0KCnAxID0gcmUuY29tcGlsZShyJyg/OlwkW0EtWl9dXHcqfFxzKSokJywgcmUuSUdOT1JFQ0FTRSkKcDIgPSByZS5jb21waWxlKHInXCRbQS1aX11cdyp8XHMrJywgcmUuSUdOT1JFQ0FTRSkKCmZvciB0aGluZyBpbiBzdHVmZjoKCWlmIHAxLm1hdGNoKHRoaW5nKToKCQlwcmludChwMi5maW5kYWxsKHRoaW5nKSkK