@dispatch(Symbol)
def _lean(expr, fields=None):
    if not fields or set(expr.fields).issubset(fields):
        return expr, fields
    else:
        return expr[sorted(fields)], fields
If application state for local state is unknown, don't do anything.
dataset/ETHPy150Open blaze/blaze/blaze/expr/optimize.py/_lean--crossover with--dataset/ETHPy150Open ClusterHQ/flocker/flocker/node/test/test_container.py/ApplicationNodeDeployerCalculateChangesTests.test_unknown_applications