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    "# Working with Lists in Functions\n",
    "#### CS 65/STEM 280: Introduction to Computer Science I"
   ]
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    "## Lists as arguments and return values\n",
    "\n",
    "You can normally use lists as arguments and return values just fine, though there's a slight nuance to be aware of. "
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      "4\n"
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    "def double_val(param):\n",
    "    param = param * 2\n",
    "\n",
    "x = 4\n",
    "double_val(x)\n",
    "print(x)"
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      "[8]\n"
     ]
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   "source": [
    "def double_list(param):\n",
    "    param[0] = param[0] * 2\n",
    "\n",
    "x = [4]\n",
    "double_list(x)\n",
    "print(x)"
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    "## Why does this happen?\n",
    "\n",
    "Big objects like collections are really stored in a different part of memory which is _referenced_ by the variable name.\n",
    "\n",
    "When you pass one of these objects as an argument, the parameter is really a copy of the reference, _not the value itself_.\n",
    "\n",
    "Small objects like ints and floats really do get copied to the parameter."
   ]
  }
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