--- test case: "123" in: str: "123" out: str: "123" --- test case: " 123" in: str: " 123" out: str: "123" --- test case: "123 " in: str: "123 " out: str: "123" --- test case: " 123 " in: str: " 123 " out: str: "123" --- test case: " 123" in: str: " 123" out: str: "123" --- test case: "123 " in: str: "123 " out: str: "123" --- test case: " 123 " in: str: " 123 " out: str: "123" --- test case: "\"123\"" in: str: "\"123\"" out: str: "123" --- test case: " \"123\"" in: str: " \"123\"" out: str: "123" --- test case: "\"123\" " in: str: "\"123\" " out: str: "123" --- test case: " \"123\" " in: str: " \"123\" " out: str: "123" --- test case: " \"123\"" in: str: " \"123\"" out: str: "123" --- test case: "\"123\" " in: str: "\"123\" " out: str: "123" --- test case: " \"123\" " in: str: " \"123\" " out: str: "123" --- test case: "" in: str: "" out: str: "" --- test case: "\"" in: str: "\"" out: str: "\"" --- test case: "\"\"" in: str: "\"\"" out: str: "" --- test case: "\" \"" in: str: "\" \"" out: str: " " --- test case: " \"" in: str: " \"" out: str: "\"" --- test case: " \"\"" in: str: " \"\"" out: str: "" --- test case: " \" \"" in: str: " \" \"" out: str: " " --- test case: "\" " in: str: "\" " out: str: "\"" --- test case: "\"\" " in: str: "\"\" " out: str: "" --- test case: "\" \" " in: str: "\" \" " out: str: " " --- test case: " \" " in: str: " \" " out: str: "\"" --- test case: " \"\" " in: str: " \"\" " out: str: "" --- test case: " \" \" " in: str: " \" \" " out: str: " " --- test case: "\"123 \"" in: str: "\"123 \"" out: str: "123 " --- test case: "\" 123\"" in: str: "\" 123\"" out: str: " 123" --- test case: "\" 123 \"" in: str: "\" 123 \"" out: str: " 123 " --- test case: " \"123 \"" in: str: " \"123 \"" out: str: "123 " --- test case: " \" 123\"" in: str: " \" 123\"" out: str: " 123" --- test case: " \" 123 \"" in: str: " \" 123 \"" out: str: " 123 " --- test case: "\"123 \" " in: str: "\"123 \" " out: str: "123 " --- test case: "\" 123\" " in: str: "\" 123\" " out: str: " 123" --- test case: "\" 123 \" " in: str: "\" 123 \" " out: str: " 123 " --- test case: " \"123 \" " in: str: " \"123 \" " out: str: "123 " --- test case: " \" 123\" " in: str: " \" 123\" " out: str: " 123" --- test case: " \" 123 \" " in: str: " \" 123 \" " out: str: " 123 " --- test case: "+" in: str: "+" out: str: "+" --- test case: "++" in: str: "++" out: str: "++" --- test case: "+123" in: str: "+123" out: str: "+123" --- test case: "++123" in: str: "++123" out: str: "++123" --- test case: "+\"123\"" in: str: "+\"123\"" out: str: "+\"123\"" --- test case: " \"+123\" " in: str: " \"+123\" " out: str: "+123" --- test case: " \"+\" " in: str: " \"+\" " out: str: "+" --- test case: " \"+ \" " in: str: " \"+ \" " out: str: "+ " --- test case: " \" +\" " in: str: " \" +\" " out: str: " +" --- test case: " \" + \" " in: str: " \" + \" " out: str: " + " ...