#NEWLINE# def lean_projection( expr ) : #NEWLINE# #INDENT# " Insert projections to keep dataset as thin as possible\n\n    >>> t = symbol('t', 'var * {a: int, b: int, c: int, d: int}')\n    >>> lean_projection(t.sort('a').b)\n    t[['a', 'b']].sort('a', ascending=True).b\n    " #NEWLINE# fields = expr . fields #NEWLINE# return _lean ( expr , fields = expr ) [ 0 ]