makeSizedDelim = function(delim, size, options, mode) {
                    // < and > turn into \langle and \rangle in delimiters
                    if (delim === "<" || delim === "\\lt") {
                        delim = "\\langle";
                    } else if (delim === ">" || delim === "\\gt") {
                        delim = "\\rangle";
                    }

                    // Sized delimiters are never centered.
                    if (utils.contains(stackLargeDelimiters, delim) ||
                        utils.contains(stackNeverDelimiters, delim)) {
                        return makeLargeDelim(delim, size, false, options, mode);
                    } else if (utils.contains(stackAlwaysDelimiters, delim)) {
                        return makeStackedDelim(
                            delim, sizeToMaxHeight[size], false, options, mode);
                    } else {
                        throw new ParseError("Illegal delimiter: '" + delim + "'");
                    }
                }
This file converts a parse tree into a cooresponding MathML tree. The main
entry point is the `buildMathML` function, which takes a parse tree from the
parser.