为什么此代码不从源返回另一个打印值

Question

keywords = ['PRINT']

class Lexer:
    def __init__(self, source):
        self.source = source
        self.sourceLen = len(source)
        self.cur = 0
        pass
    def getChar(self):
        if self.cur < self.sourceLen:
            return self.source[self.cur]
             
        return ""

    def next(self):
        self.cur += 1
        pass
    def skipNewline(self):
        while self.getChar() == '\n':
            self.next()
    def skipWhitespace(self):
        while self.getChar() == ' ':
            self.next()
    def skipBlanks(self):
        while self.getChar() == ' ' or self.getChar() == '\n':
            self.next()


    def tokenize(self):
        self.skipBlanks()
        curToken = ''
        char = self.getChar() # P
        
        if char in '"Hello, world!"'.split():
            curToken = ''
            return

        while char != ' ':
            curToken += char
            self.next()
            char = self.getChar()

        if curToken in keywords:
            print({"Token":curToken})
            curToken = ''


    def start(self):
        self.skipBlanks()
        
        while self.cur < self.sourceLen:
            self.tokenize()




source = """
PRINT "Hello, world!"
PRINT "second line!"
"""

lexme = Lexer(source)
lexme.start()