A FQLFragment is created when calling the fql tagged template function and can be passed as an argument to other Querys.
const num = 17;
const query1 = fql`${num} + 3)`;
const query2 = fql`5 + ${query1})`;
// produces
{ "fql": ["5 + ", { "fql": [{ "value": { "@int": "17" } }, " + 3"] }] }
A piece of an interpolated query. Interpolated Queries can be safely composed together without concern of query string injection.