@bem.decl: subtracting declarations

const BemDecl = require('@bem/sdk.decl'); const BemCell = require('@bem/sdk.cell'); const BemEntityName = require('@bem/sdk.entity-name'); const set1 = [ new BemCell({ entity: new BemEntityName({ block: 'a' }) }), new BemCell({ entity: new BemEntityName({ block: 'b' }) }), new BemCell({ entity: new BemEntityName({ block: 'c' }) }) ]; const set2 = [ new BemCell({ entity: new BemEntityName({ block: 'b' }) }), ]; const set3 = [ new BemCell({ entity: new BemEntityName({ block: 'c' }) }) ]; BemDecl.subtract(set1, set2, set3).map(c => c.id);