<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get (self, feature):
 """ Returns all values of 'feature'. """

        if type(feature) == type([]):
            feature = feature[0]
        if not isinstance(feature, b2.build.feature.Feature):
            feature = b2.build.feature.get(feature)
        assert isinstance(feature, b2.build.feature.Feature)

        if self.feature_map_ is None:
            self.feature_map_ = {}

            for v in self.all_:
                if v.feature not in self.feature_map_:
                    self.feature_map_[v.feature] = []
                self.feature_map_[v.feature].append(v.value)

        return self.feature_map_.get(feature, [])