Session4-update_class.ipynb

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   "source": [
    "### Functions - The building blocks of programming\n"
   ]
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   "source": [
    "#Analogy: functions are like the cells of a program. Up until now we learned all the signalling pathways, proteins, and genes avaialble to us. Now we can make cells that do things"
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   "source": [
    "#Different cells can come together to make a working organism or program"
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   "source": [
    "#Typically, the main function that runs your program is called main\n",
    "\n"
   ]
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   "source": [
    "#To run a function, simply write its name()\n"
   ]
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   "source": [
    "#What if we want our function to be more flexible?\n",
    "\n"
   ]
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   "source": [
    "#my_string is called the function's argument or parameter. \n",
    "#an argument is anything you 'pass' or 'feed into' the function "
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   "source": [
    "#Now we can make our function print anything we pass to it as an argument\n",
    "main('Self directed learning is great')"
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   "source": [
    "#What if we wanted to have a default argument if none is passed?\n",
    "#We use keyword arguments\n"
   ]
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   "source": [
    "You can pass multiple inputs into a function! "
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   "source": [
    "## why did nothing happen? :(  "
   ]
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   "source": [
    "Function definitions specifies what the functions do, but do not actually cause the funciton to execute! In programming language, we must ***call*** the function when we want to get an output. "
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   "source": [
    "### Value Returning Funcitons: a function that returns a value back to the part of the program that called it"
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   "source": [
    "## IMPORTANT: \n",
    "If a function contains no return statement, the value None is automatically returned."
   ]
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   "source": [
    "\n"
   ]
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   "source": [
    "\n",
    "    "
   ]
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   "source": [
    "#Why did that not work? \n",
    "#Functions only know about variables that are passed to them in brackets, or created inside of them"
   ]
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   "source": [
    "#Let's try again\n"
   ]
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   "source": [
    "## Input Validation and Stupid Proofing "
   ]
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   "source": [
    "### The goal of programs is to make them stupid proof. i.e. if you let a monkey go nuts on the keyboard, \n",
    "### it should not break your program with errors"
   ]
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   "source": [
    "#e.g.\n",
    "\n"
   ]
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   "source": [
    "### Notice our function worked until it broke\n",
    "#### The error listed is : Index Error"
   ]
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   "source": [
    "#To avoid this, we use something called a try / except block\n",
    "#Lets copy our code over and fix this buffoonery\n",
    "\n"
   ]
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   "source": [
    "## We use try/except to prevent errors when users don't follow the instructions\n",
    "### i.e. input a number when they should have inputed a string\n",
    "\n",
    "\n",
    "\n"
   ]
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   "source": [
    "#Stupid proof version\n"
   ]
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