diff --git a/exercises b/exercises
index 4ff8f9c..28be2c5 100644
--- a/exercises
+++ b/exercises
@@ -24,7 +24,9 @@ take the following input data
         "name": "Gill",
         "type": "fish"
     }
-]1. and group them by type
+]
+
+1. and group them by type
 ex:
 [
     {
@@ -35,9 +37,15 @@ ex:
         type: dog,
         animals: ['Manuel', 'Sparky', 'John']
     }, etc...
-]2. Given 2-3 animals that are in the list create an interesction of the list.
-ex: given manuel and gill, intersect with the list of animals. Some animals may NOT appear in both lists, handle that case!3. Given an array, generate a CSV representation of that array with a set of headers.
+]
+
+2. Given 2-3 animals that are in the list create an interesction of the list.
+ex: given manuel and gill, intersect with the list of animals. Some animals may NOT appear in both lists, handle that case!
+
+3. Given an array, generate a CSV representation of that array with a set of headers.
 ex:
 NAME, TYPE
 Gill, fish
-Manuel, dog4. Create a function that can only run once and throws if it gets called again.5. Create a function that is given a set of functions and a set of data which are inputs for those functions and returns the one that finished the fastest out of them, displaying ms time
\ No newline at end of file
+Manuel, dog
+
+4. Create a function that can only run once and throws if it gets called again.5. Create a function that is given a set of functions and a set of data which are inputs for those functions and returns the one that finished the fastest out of them, displaying ms time
\ No newline at end of file
diff --git a/group.ts b/group.ts
index 08d32bb..38a6ce0 100644
--- a/group.ts
+++ b/group.ts
@@ -1,9 +1,9 @@
 interface DataEntry {
-    name: 'John' | 'Sparky' | 'Nova' | 'Manuel' | 'Caesar' | 'Gill';
-    type: 'dog' | 'cat' | 'fish';
+    name: 'John' | 'Sparky' | 'Nova' | 'Manuel' | 'Caesar' | 'Gill' | 'Billy' | 'Silly';
+    type: 'dog' | 'cat' | 'fish' | 'bug' | 'bird';
 };
 
-const data:Array<DataEntry> = [
+const data1: Array<DataEntry> = [
     {
         "name": "John",
         "type": "dog"
@@ -30,11 +30,30 @@ const data:Array<DataEntry> = [
     }
 ];
 
+const data2: Array<DataEntry> = [
+    {
+        "name": "John",
+        "type": "dog"
+    },
+        {
+        "name": "Sparky",
+        "type": "dog"
+    },
+    {
+        "name": "Silly",
+        "type": "bug"
+    },
+        {
+        "name": "Billy",
+        "type": "bird"
+    }
+]
+
 interface OutputEntry {
     type: string;
     animals: Array<string>;
 }
-    
+
 
 const groupByType = (ar: Array<DataEntry>) => {
     return ar.reduce((acc:Array<OutputEntry>, element:DataEntry): Array<OutputEntry> => {
@@ -51,5 +70,44 @@ const groupByType = (ar: Array<DataEntry>) => {
     }, [] as Array<OutputEntry>);
 }
 
-const elements = groupByType(data);
-console.log(elements);
\ No newline at end of file
+// 1 - group by type
+const elements = groupByType(data1);
+console.log(elements);
+
+// 2 - data intersection
+const intersection = (ar1: Array<DataEntry>, ar2: Array<DataEntry>): Array<DataEntry>  => {
+    return ar1.reduce((acc: Array<DataEntry>, el1: DataEntry): Array<DataEntry>  => {
+        const result: DataEntry | void =  ar2.find((el2: DataEntry): any => el2.name === el1.name && el2.type === el1.type);
+        if (result) {
+            acc.push(result);
+        }
+
+        return acc;
+    }, [] as Array<DataEntry>);
+};
+
+console.log( intersection(data1, data2));
+
+// 3 - generate a csv
+const CSVFormater = (content: Array<Array<string>>): string => {
+    const result = content.map((line: Array<string>): string => line.join(','));
+
+    return result.join('\n')
+};
+
+const CSVGeneartor = (ar: Array<DataEntry>): string => {
+    if (ar.length === 0) {
+        return '';
+    }
+
+    const header = Object.keys(ar[0]);
+    const content = [];
+    content.push(header);
+    ar.forEach((el: DataEntry): void => {
+        content.push(Object.values(el));
+    });
+
+    return CSVFormater(content);
+}
+
+console.log( '---', CSVGeneartor(data1));
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
new file mode 100644
index 0000000..48e341a
--- /dev/null
+++ b/package-lock.json
@@ -0,0 +1,3 @@
+{
+  "lockfileVersion": 1
+}
diff --git a/tsconfig.json b/tsconfig.json
index b2b55da..e54d828 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -2,7 +2,7 @@
   "compilerOptions": {
     /* Basic Options */
     // "incremental": true,                   /* Enable incremental compilation */
-    "target": "es6",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */
+    "target": "ES2017",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */
     "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
     // "lib": [],                             /* Specify library files to be included in the compilation. */
     // "allowJs": true,                       /* Allow javascript files to be compiled. */