Function asCall

scripts/rubi/extract-rules.ts:64–66

(expr: Json, op: string)

}

function asCall(expr: Json, op: string): Json[] | null {
  return Array.isArray(expr) && expr[0] === op ? (expr as Json[]) : null;
}

/** Net bracket depth of a fragment, ignoring brackets inside strings. */
function bracketBalance(s: string): number {