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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def parse(self, lines):
 """Parse the input lines from a robots.txt file. We allow that a user-agent: line is not preceded by one or more blank lines. """

        # states:
        #   0: start state
        #   1: saw user-agent line
        #   2: saw an allow or disallow line
        state = 0
        entry = Entry()

        for line in lines:
            if not line:
                if state == 1:
                    entry = Entry()
                    state = 0
                elif state == 2:
                    self._add_entry(entry)
                    entry = Entry()
                    state = 0
            # remove optional comment and strip line
            i = line.find('#')
            if i >= 0:
                line = line[:i]
            line = line.strip()
            if not line:
                continue
            line = line.split(':', 1)
            if len(line) == 2:
                line[0] = line[0].strip().lower()
                line[1] = urllib.parse.unquote(line[1].strip())
                if line[0] == "user-agent":
                    if state == 2:
                        self._add_entry(entry)
                        entry = Entry()
                    entry.useragents.append(line[1])
                    state = 1
                elif line[0] == "disallow":
                    if state != 0:
                        entry.rulelines.append(RuleLine(line[1], False))
                        state = 2
                elif line[0] == "allow":
                    if state != 0:
                        entry.rulelines.append(RuleLine(line[1], True))
                        state = 2
        if state == 2:
            self._add_entry(entry)