Function isCall

src/compute-engine/rubi/compile.ts:56–58

(x: Json, op: string)

  skipped: { id: string; reason: string }[];
};

const SLOT = 'RUBIPAT_';
const OPT = 'RUBIOPT_';
const VAR = 'RUBIPATVARX';

function isCall(x: Json, op: string): x is Json[] {