materialize(flags) {
      flags = flags || ALL;
      const p = this;
      if (flags & ADD && p.addF) {
        p.add = materialize(p.add, p.addF);
        p.addF = null;
      }
      if (flags & REM && p.remF) {
        p.rem = materialize(p.rem, p.remF);
        p.remF = null;
      }
      if (flags & MOD$1 && p.modF) {
        p.mod = materialize(p.mod, p.modF);
        p.modF = null;
      }
      if (flags & SOURCE && p.srcF) {
        p.source = p.source.filter(p.srcF);
        p.srcF = null;
      }
      return p;
    }
Materialize one or more tuple sets in this pulse. If the tuple set(s) have
a registered filter function, it will be applied and the tuple set(s) will
be replaced with materialized tuple arrays.
@param {number} flags - Flags indicating the tuple set(s) to materialize.
@return {Pulse} - Returns this pulse instance.