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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 from_text(text):
 """Convert text into a DNS rdata class value. @param text: the text @type text: string @rtype: int @raises dns.rdataclass.UnknownRdataClass: the class is unknown @raises ValueError: the rdata class value is not >= 0 and <= 65535 """


    value = _by_text.get(text.upper())
    if value is None:
        match = _unknown_class_pattern.match(text)
        if match == None:
            raise UnknownRdataclass
        value = int(match.group(1))
        if value < 0 or value > 65535:
            raise ValueError("class must be between >= 0 and <= 65535")
    return value