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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 element_id_by_label(browser, label):
 """Return the id of a label's for attribute"""

    label = XPathSelector(browser,
                          unicode('//label[contains(., "%s")]' % label))
    if not label:
        return False
    return label.get_attribute('for')