def build_item_features(self, data, normalize=True):
builder = _FeatureBuilder(<EOL>self._item_id_mapping,<EOL>self._item_feature_mapping,<EOL>self._item_identity_features,<EOL>normalize,<EOL>"<STR_LIT>",<EOL>)<EOL>return builder.build(data)<EOL>
Build a item features matrix out of an iterable of the form
(item id, [list of feature names]) or (item id, {feature name: feature weight}).

Parameters
----------

data: iterable of the form
    (item id, [list of feature names]) or (item id,
    {feature name: feature weight}).
    Item and feature ids will be translated to internal indices
    constructed during the fit call.
normalize: bool, optional
    If true, will ensure that feature weights sum to 1 in every row.

Returns
-------

feature matrix: CSR matrix (num items, num features)
    Matrix of item features.