fixed xml:id tag

Author: habibasorour

source/ch8_filehandling.ptx

@@ -340,17 +340,17 @@ public class CreateFile {
         <p>
             And that's it! We will add our code to the foundational code for a complete program. First, <xref ref="file-write-full-python" text="type-global"/> shows the completed Python code.
         </p>
-        <data xml:id="my-file-8-4-2">
+        <data xml:id="data-file-write-full-python">
             <title>Data file for writing example</title>
-        <datafile label="my-file-8-4-4" filename="myfile.txt" xml:id= "my-file-8-4-4" editable="yes">
+        <datafile label="data-file-write-full-python" filename="myfile.txt" editable="yes">
                 <pre>
 
                 </pre>
         </datafile>
         </data>
 
         <listing xml:id="file-write-full-python">
-        <program interactive="activecode" language="python" add-files="my-file-8-4-4">
+        <program interactive="activecode" language="python" add-files="data-file-write-full-python">
             <code>
             try:
                 with open("myfile.txt", "w") as my_writer:
@@ -367,14 +367,14 @@ public class CreateFile {
         <p>
            <xref ref="file-write-full-java" text="type-global"/> shows the completed Java code. 
         </p>
-        <data xml:id="my-file-8-4-5">
+        <data xml:id="data-file-write-full-java">
             <title>Data file for writing example</title>
-        <datafile label="my-file-8-4-5" filename="myfile.txt" xml:id= "my-file-8-4-5" editable="yes">
+        <datafile label="data-file-write-full-java" filename="myfile.txt" editable="yes">
                 <pre>
 
                 </pre>
             </datafile>
-        <program xml:id="file-write-full-java" interactive="activecode" language="java" add-files = "my-file-8-4-5">
+        <program xml:id="file-write-full-java" interactive="activecode" language="java" add-files = "data-file-write-full-java">
             <code>
             import java.io.FileWriter;
             import java.io.IOException;
@@ -415,17 +415,17 @@ public class CreateFile {
         <p>
             Now, when we use <c>write()</c> method like before, the text will be appended if there is already tSext in the document. If we were to update our code to include the <c>boolean</c> argument as shown in <xref ref="file-write-with-append" text="type-global"/>. 
 
-        <data xml:id="my-file-8-4-6">
+        <data xml:id="data-file-write-with-append">
             <title>Data file for writing example</title>
-        <datafile label="my-file-8-4-6" filename="myfile" editable="yes">
+        <datafile label="data-file-write-with-append" filename="myfile" editable="yes">
                 <pre>
 
                 </pre>
             </datafile>
         </data>
 
         <listing xml:id="file-write-with-append">
-        <program interactive="activecode" language="java" add-files = "my-file-8-4-6">
+        <program interactive="activecode" language="java" add-files = "data-file-write-with-append">
             <code>
             import java.io.FileWriter;
             import java.io.IOException;