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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 lookup(self, label):
        ''' take a field_name_label and return the id'''
        if self.is_child:
            try:
                return self._children[label]
            except KeyError:
                self._children[label] = ChildFieldPicklist(self.parent, 
                                                           label, 
                                                           self.field_name) 
                return self._children[label]
        else:
            return get_label_value(label, self._picklist)