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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 __search_text_check_convert(cls, text):
 """Converts and keeps only words in text deemed to be valid"""

        text = cls.check_convert_string(text, name='text', no_leading_trailing_whitespace=False)
        if len(text) > VALIDATION_META_SEARCH_TEXT:
            raise ValueError("Search text can contain at most %d characters" % VALIDATION_META_SEARCH_TEXT)
        text = ' '.join(_PATTERN_WORDS.findall(text))
        if not text:
            raise ValueError('Search text must contain at least one non-whitespace term (word)')
        return text