add solution week 185 task 2 in python

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+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "476288d6",
+   "metadata": {},
+   "source": [
+    "# Task 2: Mask Code\n",
+    "\n",
+    "You are given a list of codes in many random format.\n",
+    "\n",
+    "Write a script to mask first four characters (a-z,0-9) and keep the rest as it is.\n",
+    "Example 1\n",
+    "```\n",
+    "Input: @list = ('ab-cde-123', '123.abc.420', '3abc-0010.xy')\n",
+    "Output: ('xx-xxe-123', 'xxx.xbc.420', 'xxxx-0010.xy')\n",
+    "```\n",
+    "Example 2\n",
+    "```\n",
+    "Input: @list = ('1234567.a', 'a-1234-bc', 'a.b.c.d.e.f')\n",
+    "Output: ('xxxx567.a', 'x-xxx4-bc', 'x.x.x.x.e.f')\n",
+    "````"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "id": "2226efbf",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import re"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "id": "ba2106d7",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "ex1 = ('ab-cde-123', '123.abc.420', '3abc-0010.xy')\n",
+    "ex2 = ('1234567.a', 'a-1234-bc', 'a.b.c.d.e.f')"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "65f5f1bb",
+   "metadata": {},
+   "source": [
+    "First step is to mask a single code using pythons re.sub(). re.sub has a named argument ```count=4``` which will substitute the required number of matches.  \\w regex matches alphanumeric characters."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "id": "56d192cb",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "'xx-xxe-123'"
+      ]
+     },
+     "execution_count": 3,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "re.sub(r'[\\w]', 'x', ex1[0], count=4)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "8834b502",
+   "metadata": {},
+   "source": [
+    "Next wrap this in a function which handles a list of codes to mask.  Using map() with a lambda function as the first argument is a common idiom in python."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "id": "54223d5f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def mask_list_of_codes(loc):\n",
+    "    result = map(lambda code: re.sub(r'[\\w]', 'x', code, count=4), loc)\n",
+    "    return list(result)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "a9daffb3",
+   "metadata": {},
+   "source": [
+    "Finally test the function with the examples above:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "id": "3aea4dac",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "['xx-xxe-123', 'xxx.xbc.420', 'xxxx-0010.xy']"
+      ]
+     },
+     "execution_count": 5,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "mask_list_of_codes(ex1)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "id": "30d532a7",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "['xxxx567.a', 'x-xxx4-bc', 'x.x.x.x.e.f']"
+      ]
+     },
+     "execution_count": 6,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "mask_list_of_codes(ex2)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.8.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}