constructor(e, t) {
    this.mode = void 0, this.gullet = void 0, this.settings = void 0, this.leftrightDepth = void 0, this.nextToken = void 0, this.mode = "math", this.gullet = new b6(e, t, this.mode), this.settings = t, this.leftrightDepth = 0;
  }
Parses an "expression", which is a list of atoms.

`breakOnInfix`: Should the parsing stop when we hit infix nodes? This
                happens when functions have higher precedence han infix
                nodes in implicit parses.

`breakOnTokenText`: The text of the token that the expression should end
                    with, or `null` if something else should end the
                    expression.