### Question:
MathMLUtils { public static boolean isNumeric(String id) { return id.matches("\\d+.?\\d*"); }  static String getEngine(); static void setEngine(String engine); static Multiset<String> extractIdentifiers(MathTag math, Boolean useTeXIdentifiers, String url); static Multiset<String> extractIdentifiersFromTex(String tex, boolean useTeX, String url); static Multiset<String> extractIdentifiersFromMathML(String mathML, Boolean useTeXIdentifiers, boolean useBlacklist); static boolean isNumeric(String id); static String texToMathML(String tex); static String cleanTexString(String tex); final static Set<String> BLACKLIST; }### Answer:
@Test public void extractFromMathML_isNumeric() throws Exception { assertFalse(MathMLUtils.isNumeric("a")); assertTrue(MathMLUtils.isNumeric("1")); assertTrue(MathMLUtils.isNumeric("10")); assertTrue(MathMLUtils.isNumeric("10.0")); assertTrue(MathMLUtils.isNumeric("10.00001")); assertFalse(MathMLUtils.isNumeric("10.00001a")); assertFalse(MathMLUtils.isNumeric("x1")); }