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+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Functions\n",
+    "\n",
+    "Like a traditional mathematical functions, python functions can take an\n",
+    "input, process it, and give an output. In python, the input variables\n",
+    "are referred to as *arguments*. Functions are blocks of code that is run\n",
+    "every time it’s called. This allows us to re-use code.\n",
+    "\n",
+    "Functions are defined by using the <code> def </code> keyword. Reminder:\n",
+    "it is important to keep track of indentations as it signifies the end of\n",
+    "the function when the indentation returns back to the same level.\n",
+    "\n",
+    "## Defining Functions\n",
+    "\n",
+    "### Simple function\n",
+    "\n",
+    "A simple function with no input variable can be useful if you need to\n",
+    "re-use code multiple times without having to re-write it.\n",
+    "\n",
+    "``` python\n",
+    "    def function_name():\n",
+    "        print(\"This is from a function\")\n",
+    "```\n",
+    "\n",
+    "### Defining a function with one input\n",
+    "\n",
+    "We can pass variables through to the function to be processed as\n",
+    "follows:\n",
+    "\n",
+    "``` python\n",
+    "    def function(x):\n",
+    "        print(x + \" is best\")\n",
+    "```\n",
+    "\n",
+    "Note input variables can be of any data type (integer, float, string,\n",
+    "etc.). \\### Returning values from a function If we want to calculate a\n",
+    "value and pass it back to the script for further use, we can use the\n",
+    "`return` keyword. Let’s define a linear function that takes two inputs,\n",
+    "`x` and `b`, computes the corresponding `y` value, and returns it so it\n",
+    "can be used elsewhere in the code.\n",
+    "\n",
+    "``` python\n",
+    "    def function(x, b):\n",
+    "        y = 3*x+b\n",
+    "        return y\n",
+    "```\n",
+    "\n",
+    "For multiple output variables we can add \\## Calling functions Now that\n",
+    "we’ve covered defining functions we want to call the function in order\n",
+    "to execute the block inside the function. To do this, we simply re-call\n",
+    "the function name as follows.\n",
+    "\n",
+    "``` python\n",
+    "function(2,-1)\n",
+    "```\n",
+    "\n",
+    "Note that when running this code, nothing happens. This is because we\n",
+    "haven’t told the computer what to do with the output. Hence, if we wish\n",
+    "to store the output then we need to use the assign operator `=`.\n",
+    "\n",
+    "``` python\n",
+    "output = function(2,-1)\n",
+    "\n",
+    "print(output)\n",
+    "```\n",
+    "\n",
+    "In case you want to return multiple output variable from a single\n",
+    "function we will have…\n",
+    "\n",
+    "## Summary\n",
+    "\n",
+    "``` python\n",
+    "def function_name(argument1, argument2, argument3):\n",
+    "    output1 = argument1 * argument2 - argument3\n",
+    "    output2 = argument2 + argument3\n",
+    "    return output1, output2\n",
+    "\n",
+    "[solution1, solution2] = function_name(1,2,3)\n",
+    "```\n",
+    "\n",
+    "-   `def` - defines a function. All the code that is indented underneath\n",
+    "    is considered inside the function block.\n",
+    "-   `function_name` - this is used to call the function block.\n",
+    "-   `argument1` (optional) - input variable. This is data that can be\n",
+    "    pass to the function. It is possible to have multiple variables\n",
+    "    separated by a comma. As well as can be omitted if the function\n",
+    "    should just give you an output such as.\n",
+    "-   `return` (optional) - if you wish to return something to your\n",
+    "    script, the return keyword is used. The keyword can be followed by\n",
+    "    an output variable or a constant. For multiple output variables,\n",
+    "    separate them by a comma."
+   ],
+   "id": "c549f9ae-7280-471e-a7e3-92d3340b7514"
+  }
+ ],
+ "nbformat": 4,
+ "nbformat_minor": 5,
+ "metadata": {}
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