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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 cbpdnmsk_class_label_lookup(label):
 """Get a ConvBPDNMask class from a label string."""


    clsmod = {'admm': admm_cbpdn.ConvBPDNMaskDcpl,
              'fista': fista_cbpdn.ConvBPDNMask}
    if label in clsmod:
        return clsmod[label]
    else:
        raise ValueError('Unknown ConvBPDNMask solver method %s' % label)