diff --git a/.gitignore b/.gitignore
index 05a1429..3d45206 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,3 @@
 **/node_modules
 **/flow-typed
-
+**/flow-coverage
diff --git a/chapter02/package-lock.json b/chapter02/package-lock.json
index add8517..7ae4963 100644
--- a/chapter02/package-lock.json
+++ b/chapter02/package-lock.json
@@ -313,6 +313,16 @@
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+            "dev": true,
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@@ -613,6 +623,12 @@
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@@ -885,6 +901,16 @@
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+            "resolved": "https://registry.npmjs.org/babel-plugin-transform-object-rest-spread/-/babel-plugin-transform-object-rest-spread-6.26.0.tgz",
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+            "dev": true,
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             "dev": true
         },
+        "badge-up": {
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+            "resolved": "https://registry.npmjs.org/badge-up/-/badge-up-2.3.0.tgz",
+            "integrity": "sha1-cv/2lKMtRKoUAx5yiJ4PxVtTBYs=",
+            "dev": true,
+            "requires": {
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@@ -1287,6 +1324,15 @@
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+            "resolved": "https://registry.npmjs.org/coa/-/coa-0.4.1.tgz",
+            "integrity": "sha1-uvb0nHrZ8gxZevObP8HlCQ/og4s=",
+            "dev": true,
+            "requires": {
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@@ -1379,6 +1425,12 @@
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+            "resolved": "https://registry.npmjs.org/css-color-names/-/css-color-names-0.0.4.tgz",
+            "integrity": "sha1-gIrcLnnPhHOAabZGyyDsJ762KeA=",
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@@ -1452,6 +1504,12 @@
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+            "integrity": "sha1-+HUL+2sDx2ZOsObLHrTGZBmvlCc=",
+            "dev": true
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@@ -1467,6 +1525,12 @@
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+            "resolved": "https://registry.npmjs.org/eastasianwidth/-/eastasianwidth-0.1.1.tgz",
+            "integrity": "sha1-RNZW3p2kFWlEZzNTZfsxR7hXK3w=",
+            "dev": true
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@@ -1808,6 +1872,21 @@
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+            "integrity": "sha1-lEvs00zEHuMqY6n68nrVpl/Fl3c=",
+            "dev": true,
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@@ -1828,6 +1907,15 @@
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@@ -1939,6 +2027,25 @@
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+            "dev": true,
+            "requires": {
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@@ -1961,12 +2068,147 @@
                 "write": "0.2.1"
             }
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+        "flow-annotation-check": {
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+            "resolved": "https://registry.npmjs.org/flow-annotation-check/-/flow-annotation-check-1.8.0.tgz",
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@@ -3047,6 +3295,28 @@
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+            "integrity": "sha1-6lo77ULG1s6ZWk+KEmm12uIjgo0=",
+            "dev": true,
+            "requires": {
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@@ -3144,6 +3414,15 @@
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+            "dev": true,
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@@ -4154,6 +4490,42 @@
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+            "resolved": "https://registry.npmjs.org/react/-/react-15.5.4.tgz",
+            "integrity": "sha1-+oPrAVBqsjfNwcjDsc6o3gEr8Ec=",
+            "dev": true,
+            "requires": {
+                "fbjs": "0.8.16",
+                "loose-envify": "1.3.1",
+                "object-assign": "4.1.1",
+                "prop-types": "15.6.1"
+            }
+        },
+        "react-dom": {
+            "version": "15.5.4",
+            "resolved": "https://registry.npmjs.org/react-dom/-/react-dom-15.5.4.tgz",
+            "integrity": "sha1-ugwoeG/VLtfk8hNf4CiNRirvk9o=",
+            "dev": true,
+            "requires": {
+                "fbjs": "0.8.16",
+                "loose-envify": "1.3.1",
+                "object-assign": "4.1.1",
+                "prop-types": "15.5.10"
+            },
+            "dependencies": {
+                "prop-types": {
+                    "version": "15.5.10",
+                    "resolved": "https://registry.npmjs.org/prop-types/-/prop-types-15.5.10.tgz",
+                    "integrity": "sha1-J5ffwxJhguOpXj37suiT3ddFYVQ=",
+                    "dev": true,
+                    "requires": {
+                        "fbjs": "0.8.16",
+                        "loose-envify": "1.3.1"
+                    }
+                }
+            }
+        },
         "read-pkg": {
             "version": "2.0.0",
             "resolved": "https://registry.npmjs.org/read-pkg/-/read-pkg-2.0.0.tgz",
@@ -4346,6 +4718,16 @@
                 "path-parse": "1.0.5"
             }
         },
+        "resolve-dir": {
+            "version": "0.1.1",
+            "resolved": "https://registry.npmjs.org/resolve-dir/-/resolve-dir-0.1.1.tgz",
+            "integrity": "sha1-shklmlYC+sXFxJatiUpujMQwJh4=",
+            "dev": true,
+            "requires": {
+                "expand-tilde": "1.2.2",
+                "global-modules": "0.2.3"
+            }
+        },
         "resolve-from": {
             "version": "1.0.1",
             "resolved": "https://registry.npmjs.org/resolve-from/-/resolve-from-1.0.1.tgz",
@@ -4401,6 +4783,12 @@
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             "dev": true
         },
+        "sax": {
+            "version": "0.6.1",
+            "resolved": "https://registry.npmjs.org/sax/-/sax-0.6.1.tgz",
+            "integrity": "sha1-VjsZx8HeiS4Jv8Ty/DDjwn8JUrk=",
+            "dev": true
+        },
         "semver": {
             "version": "5.5.0",
             "resolved": "https://registry.npmjs.org/semver/-/semver-5.5.0.tgz",
@@ -4566,6 +4954,12 @@
             "integrity": "sha1-IzTBjpx1n3vdVv3vfprj1YjmjtM=",
             "dev": true
         },
+        "strip-eof": {
+            "version": "1.0.0",
+            "resolved": "https://registry.npmjs.org/strip-eof/-/strip-eof-1.0.0.tgz",
+            "integrity": "sha1-u0P/VZim6wXYm1n80SnJgzE2Br8=",
+            "dev": true
+        },
         "strip-json-comments": {
             "version": "2.0.1",
             "resolved": "https://registry.npmjs.org/strip-json-comments/-/strip-json-comments-2.0.1.tgz",
@@ -4578,6 +4972,53 @@
             "integrity": "sha1-U10EXOa2Nj+kARcIRimZXp3zJMc=",
             "dev": true
         },
+        "svgo": {
+            "version": "0.4.5",
+            "resolved": "https://registry.npmjs.org/svgo/-/svgo-0.4.5.tgz",
+            "integrity": "sha1-ulYVX7FzNyiVbAG0BSIe5+eJoqQ=",
+            "dev": true,
+            "requires": {
+                "coa": "0.4.1",
+                "colors": "0.6.2",
+                "js-yaml": "2.1.3",
+                "sax": "0.6.1",
+                "whet.extend": "0.9.9"
+            },
+            "dependencies": {
+                "argparse": {
+                    "version": "0.1.16",
+                    "resolved": "https://registry.npmjs.org/argparse/-/argparse-0.1.16.tgz",
+                    "integrity": "sha1-z9AeD7uj1srtBJ+9dY1A9lGW9Xw=",
+                    "dev": true,
+                    "requires": {
+                        "underscore": "1.7.0",
+                        "underscore.string": "2.4.0"
+                    }
+                },
+                "colors": {
+                    "version": "0.6.2",
+                    "resolved": "https://registry.npmjs.org/colors/-/colors-0.6.2.tgz",
+                    "integrity": "sha1-JCP+ZnisDF2uiFLl0OW+CMmXq8w=",
+                    "dev": true
+                },
+                "esprima": {
+                    "version": "1.0.4",
+                    "resolved": "https://registry.npmjs.org/esprima/-/esprima-1.0.4.tgz",
+                    "integrity": "sha1-n1V+CPw7TSbs6d00+Pv0drYlha0=",
+                    "dev": true
+                },
+                "js-yaml": {
+                    "version": "2.1.3",
+                    "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-2.1.3.tgz",
+                    "integrity": "sha1-D/tWF75VUlh4Bj16Fq7n/dKC6Ew=",
+                    "dev": true,
+                    "requires": {
+                        "argparse": "0.1.16",
+                        "esprima": "1.0.4"
+                    }
+                }
+            }
+        },
         "table": {
             "version": "4.0.2",
             "resolved": "https://registry.npmjs.org/table/-/table-4.0.2.tgz",
@@ -4623,6 +5064,34 @@
                 }
             }
         },
+        "temp": {
+            "version": "0.8.3",
+            "resolved": "https://registry.npmjs.org/temp/-/temp-0.8.3.tgz",
+            "integrity": "sha1-4Ma8TSa5AxJEEOT+2BEDAU38H1k=",
+            "dev": true,
+            "requires": {
+                "os-tmpdir": "1.0.2",
+                "rimraf": "2.2.8"
+            },
+            "dependencies": {
+                "rimraf": {
+                    "version": "2.2.8",
+                    "resolved": "https://registry.npmjs.org/rimraf/-/rimraf-2.2.8.tgz",
+                    "integrity": "sha1-5Dm+Kq7jJzIZUnMPmaiSnk/FBYI=",
+                    "dev": true
+                }
+            }
+        },
+        "terminal-table": {
+            "version": "0.0.12",
+            "resolved": "https://registry.npmjs.org/terminal-table/-/terminal-table-0.0.12.tgz",
+            "integrity": "sha1-e1bQCapoKN/dEPEbZU55wGKWX6I=",
+            "dev": true,
+            "requires": {
+                "colors": "1.2.1",
+                "eastasianwidth": "0.1.1"
+            }
+        },
         "text-table": {
             "version": "0.2.0",
             "resolved": "https://registry.npmjs.org/text-table/-/text-table-0.2.0.tgz",
@@ -4689,6 +5158,18 @@
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             "dev": true
         },
+        "underscore": {
+            "version": "1.7.0",
+            "resolved": "https://registry.npmjs.org/underscore/-/underscore-1.7.0.tgz",
+            "integrity": "sha1-a7rwh3UA02vjTsqlhODbn+8DUgk=",
+            "dev": true
+        },
+        "underscore.string": {
+            "version": "2.4.0",
+            "resolved": "https://registry.npmjs.org/underscore.string/-/underscore.string-2.4.0.tgz",
+            "integrity": "sha1-jN2PusTi0uoefi6Al8QvRCKA+Fs=",
+            "dev": true
+        },
         "universalify": {
             "version": "0.1.1",
             "resolved": "https://registry.npmjs.org/universalify/-/universalify-0.1.1.tgz",
@@ -4799,6 +5280,12 @@
             "integrity": "sha1-nITsLc9oGH/wC8ZOEnS0QhduHIQ=",
             "dev": true
         },
+        "whet.extend": {
+            "version": "0.9.9",
+            "resolved": "https://registry.npmjs.org/whet.extend/-/whet.extend-0.9.9.tgz",
+            "integrity": "sha1-+HfVv2SMl+WqVC+twW1qJZucEaE=",
+            "dev": true
+        },
         "which": {
             "version": "1.3.0",
             "resolved": "https://registry.npmjs.org/which/-/which-1.3.0.tgz",
diff --git a/chapter02/package.json b/chapter02/package.json
index 894b0a7..4114359 100644
--- a/chapter02/package.json
+++ b/chapter02/package.json
@@ -9,6 +9,7 @@
         "addTypes": "flow-typed install",
         "update": "npm install && flow-typed install",
         "flow": "flow",
+        "flow-coverage": "flow-coverage-report",
         "eslint": "eslint src",
         "test": "echo \"Error: no test specified\" && exit 1"
     },
@@ -36,6 +37,14 @@
             "prefer-const": "error"
         }
     },
+    "flow-coverage-report": {
+        "concurrentFiles": 1,
+        "excludeGlob": ["node_modules/**"],
+        "includeGlob": ["src/**/*.js"],
+        "threshold": 90,
+        "type": ["text", "html", "json"]
+    },
+
     "prettier": {
         "tabWidth": 4,
         "printWidth": 75
@@ -54,6 +63,7 @@
         "eslint-config-recommended": "^2.0.0",
         "eslint-plugin-flowtype": "^2.46.1",
         "flow-bin": "^0.68.0",
+        "flow-coverage-report": "^0.5.0",
         "flow-remove-types": "^1.2.3",
         "flow-typed": "^2.4.0",
         "prettier": "^1.11.1"