def __next__(self):
if self.tokens:<EOL><INDENT>other = self.copy()<EOL>tok = other.tokens.pop()<EOL>other.tokens.append(next(tok))<EOL>return other<EOL><DEDENT>else:<EOL><INDENT>return Version.inf<EOL><DEDENT>
Return 'next' version. Eg, next(1.2) is 1.2_