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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 int_filter(text):
 """Extract integer from text. **中文文档** 摘除文本内的整数。 """

    res = list()
    for char in text:
        if char.isdigit():
            res.append(char)
    return int("".join(res))