#55 use IStringX as output for usage for cleaner jshell output

Author: axkr

symja_android_library/matheclipse-core/src/main/java/org/matheclipse/core/expression/F.java

@@ -5837,7 +5837,7 @@ public static ISymbol symbol(final String symbolName, IAST assumptionAST, EvalEn
 	 * @param head
 	 * @return
 	 */
-	public final static String usage(final ISymbol head) {
+	public final static IStringX usage(final ISymbol head) {
 		return usage(head.toString());
 	}
 
@@ -5847,10 +5847,10 @@ public final static String usage(final ISymbol head) {
 	 * @param symbolName
 	 * @return
 	 */
-	public final static String usage(final String symbolName) {
+	public final static IStringX usage(final String symbolName) {
 		StringBuilder buf = new StringBuilder();
 		Documentation.usageDocumentation(buf, symbolName);
-		return buf.toString();
+		return F.stringx(buf.toString());
 	}
 
 	/**