Added examples of what this type is

It's not pd.nan.

data/data-pipeline/notebooks/float-to-int-missing-data.ipynb

@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "code",
-   "execution_count": 18,
+   "execution_count": 2,
    "id": "cd5233fd-8ace-43c8-98c0-7db75447d7d9",
    "metadata": {},
    "outputs": [],
@@ -13,7 +13,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 19,
+   "execution_count": 3,
    "id": "1e478534-dabf-4f6d-a9fd-9553c2c3ad5c",
    "metadata": {},
    "outputs": [],
@@ -25,7 +25,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 20,
+   "execution_count": 4,
    "id": "88d362e7-d0e6-4ac8-9795-6db75f367099",
    "metadata": {},
    "outputs": [
@@ -92,7 +92,7 @@
        "d  NaN  NaN  NaN"
       ]
      },
-     "execution_count": 20,
+     "execution_count": 4,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -103,7 +103,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 21,
+   "execution_count": 5,
    "id": "b63a77da-3ede-4997-a374-10cb74d93df5",
    "metadata": {},
    "outputs": [
@@ -170,7 +170,7 @@
        "d  <NA>  NaN  NaN"
       ]
      },
-     "execution_count": 21,
+     "execution_count": 5,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -182,33 +182,128 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 22,
+   "execution_count": 11,
    "id": "99958e76-edcf-4e3e-aee8-2bfd3c1213d6",
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "a       1\n",
+       "True"
-       "b       1\n",
-       "c       1\n",
-       "d    <NA>\n",
-       "Name: X, dtype: Int64"
       ]
      },
-     "execution_count": 22,
+     "execution_count": 11,
      "metadata": {},
      "output_type": "execute_result"
     }
    ],
    "source": [
-    "df[\"X\"]"
+    "df[\"X\"][\"d\"] is pd.NA"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "id": "029f3277-af92-48b6-83bf-7dd16bbbec40",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "False"
+      ]
+     },
+     "execution_count": 12,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "df[\"X\"][\"c\"] is pd.NA"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "id": "b111b0dc-efe5-4a0c-95b7-e29108c43432",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style scoped>\n",
+       "    .dataframe tbody tr th:only-of-type {\n",
+       "        vertical-align: middle;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>X</th>\n",
+       "      <th>Y</th>\n",
+       "      <th>Z</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>a</th>\n",
+       "      <td>1</td>\n",
+       "      <td>2.0</td>\n",
+       "      <td>3.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>b</th>\n",
+       "      <td>1</td>\n",
+       "      <td>2.0</td>\n",
+       "      <td>3.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>c</th>\n",
+       "      <td>1</td>\n",
+       "      <td>2.0</td>\n",
+       "      <td>3.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>d</th>\n",
+       "      <td>0</td>\n",
+       "      <td>0.0</td>\n",
+       "      <td>0.0</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   X    Y    Z\n",
+       "a  1  2.0  3.0\n",
+       "b  1  2.0  3.0\n",
+       "c  1  2.0  3.0\n",
+       "d  0  0.0  0.0"
+      ]
+     },
+     "execution_count": 13,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "df.fillna(0)"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "029f3277-af92-48b6-83bf-7dd16bbbec40",
+   "id": "bb796b5f-37b4-4ea8-9d79-54157bfadce4",
    "metadata": {},
    "outputs": [],
    "source": []