Concatenate every character if it is escaped

main.go

@@ -67,7 +67,7 @@ func shuntingYard(re string) []postfixNode {
 			}
 			continue
 		}
-		if re_runes[i] != '(' && re_runes[i] != '|' && re_runes[i] != '\\' {
+		if (re_runes[i] != '(' && re_runes[i] != '|' && re_runes[i] != '\\') || (i > 0 && re_runes[i-1] == '\\') { // Every character should be concatenated if it is escaped
 			if i < len(re_runes)-1 {
 				if re_runes[i+1] != '|' && re_runes[i+1] != '*' && re_runes[i+1] != '+' && re_runes[i+1] != '?' && re_runes[i+1] != ')' {
 					re_postfix = append(re_postfix, CONCAT)