diff --git a/example/package-lock.json b/example/package-lock.json
index 5df1e7a..01a4bf8 100644
--- a/example/package-lock.json
+++ b/example/package-lock.json
@@ -1769,7 +1769,8 @@
     "ansi": {
       "version": "0.3.1",
       "resolved": "https://registry.npmjs.org/ansi/-/ansi-0.3.1.tgz",
-      "integrity": "sha1-DELU+xcWDVqa8eSEus4cZpIsGyE="
+      "integrity": "sha1-DELU+xcWDVqa8eSEus4cZpIsGyE=",
+      "optional": true
     },
     "ansi-colors": {
       "version": "1.1.0",
@@ -1832,7 +1833,8 @@
     "ansi-wrap": {
       "version": "0.1.0",
       "resolved": "https://registry.npmjs.org/ansi-wrap/-/ansi-wrap-0.1.0.tgz",
-      "integrity": "sha1-qCJQ3bABXponyoLoLqYDu/pF768="
+      "integrity": "sha1-qCJQ3bABXponyoLoLqYDu/pF768=",
+      "optional": true
     },
     "anymatch": {
       "version": "2.0.0",
@@ -2148,7 +2150,8 @@
     "array-filter": {
       "version": "0.0.1",
       "resolved": "https://registry.npmjs.org/array-filter/-/array-filter-0.0.1.tgz",
-      "integrity": "sha1-fajPLiZijtcygDWB/SH2fKzS7uw="
+      "integrity": "sha1-fajPLiZijtcygDWB/SH2fKzS7uw=",
+      "optional": true
     },
     "array-flatten": {
       "version": "2.1.2",
@@ -2169,12 +2172,14 @@
     "array-map": {
       "version": "0.0.0",
       "resolved": "https://registry.npmjs.org/array-map/-/array-map-0.0.0.tgz",
-      "integrity": "sha1-iKK6tz0c97zVwbEYoAP2b2ZfpmI="
+      "integrity": "sha1-iKK6tz0c97zVwbEYoAP2b2ZfpmI=",
+      "optional": true
     },
     "array-reduce": {
       "version": "0.0.0",
       "resolved": "https://registry.npmjs.org/array-reduce/-/array-reduce-0.0.0.tgz",
-      "integrity": "sha1-FziZ0//Rx9k4PkR5Ul2+J4yrXys="
+      "integrity": "sha1-FziZ0//Rx9k4PkR5Ul2+J4yrXys=",
+      "optional": true
     },
     "array-slice": {
       "version": "0.2.3",
@@ -2673,6 +2678,7 @@
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/basic-auth/-/basic-auth-2.0.1.tgz",
       "integrity": "sha512-NF+epuEdnUYVlGuhaxbbq+dvJttwLnGY+YixlXlME5KpQ5W3CnXA5cVTneY3SPbPDRkcjMbifrwmFYcClgOZeg==",
+      "optional": true,
       "requires": {
         "safe-buffer": "5.1.2"
       }
@@ -3116,7 +3122,8 @@
     "chardet": {
       "version": "0.4.2",
       "resolved": "https://registry.npmjs.org/chardet/-/chardet-0.4.2.tgz",
-      "integrity": "sha1-tUc7M9yXxCTl2Y3IfVXU2KKci/I="
+      "integrity": "sha1-tUc7M9yXxCTl2Y3IfVXU2KKci/I=",
+      "optional": true
     },
     "chokidar": {
       "version": "2.1.8",
@@ -4179,6 +4186,7 @@
       "version": "1.5.1",
       "resolved": "https://registry.npmjs.org/errorhandler/-/errorhandler-1.5.1.tgz",
       "integrity": "sha512-rcOwbfvP1WTViVoUjcfZicVzjhjTuhSMntHh6mW3IrEiyE6mJyXvsToJUJGlGlw/2xU9P5whlWNGlIDVeCiT4A==",
+      "optional": true,
       "requires": {
         "accepts": "~1.3.7",
         "escape-html": "~1.0.3"
@@ -4686,9 +4694,9 @@
       "dev": true
     },
     "eventsource": {
-      "version": "1.0.7",
-      "resolved": "https://registry.npmjs.org/eventsource/-/eventsource-1.0.7.tgz",
-      "integrity": "sha512-4Ln17+vVT0k8aWq+t/bF5arcS3EpT9gYtW66EPacdj/mAFevznsnyoHLPy2BA8gbIQeIHoPsvwmfBftfcG//BQ==",
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/eventsource/-/eventsource-1.1.1.tgz",
+      "integrity": "sha512-qV5ZC0h7jYIAOhArFJgSfdyz6rALJyb270714o7ZtNnw2WSJ+eexhKtE0O8LYPRsHZHf2osHKZBxGPvm3kPkCA==",
       "dev": true,
       "requires": {
         "original": "^1.0.0"
@@ -4826,6 +4834,7 @@
       "version": "2.2.0",
       "resolved": "https://registry.npmjs.org/external-editor/-/external-editor-2.2.0.tgz",
       "integrity": "sha512-bSn6gvGxKt+b7+6TKEv1ZycHleA7aHhRHyAqJyp5pbUFuYYNIzpZnQDk7AsYckyWdEnTeAnay0aCy2aV6iTk9A==",
+      "optional": true,
       "requires": {
         "chardet": "^0.4.0",
         "iconv-lite": "^0.4.17",
@@ -5520,7 +5529,8 @@
         },
         "ansi-regex": {
           "version": "2.1.1",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "aproba": {
           "version": "1.2.0",
@@ -5538,11 +5548,13 @@
         },
         "balanced-match": {
           "version": "1.0.0",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "brace-expansion": {
           "version": "1.1.11",
           "bundled": true,
+          "optional": true,
           "requires": {
             "balanced-match": "^1.0.0",
             "concat-map": "0.0.1"
@@ -5555,15 +5567,18 @@
         },
         "code-point-at": {
           "version": "1.1.0",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "concat-map": {
           "version": "0.0.1",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "console-control-strings": {
           "version": "1.1.0",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "core-util-is": {
           "version": "1.0.2",
@@ -5666,7 +5681,8 @@
         },
         "inherits": {
           "version": "2.0.3",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "ini": {
           "version": "1.3.5",
@@ -5676,6 +5692,7 @@
         "is-fullwidth-code-point": {
           "version": "1.0.0",
           "bundled": true,
+          "optional": true,
           "requires": {
             "number-is-nan": "^1.0.0"
           }
@@ -5688,17 +5705,20 @@
         "minimatch": {
           "version": "3.0.4",
           "bundled": true,
+          "optional": true,
           "requires": {
             "brace-expansion": "^1.1.7"
           }
         },
         "minimist": {
           "version": "0.0.8",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "minipass": {
           "version": "2.3.5",
           "bundled": true,
+          "optional": true,
           "requires": {
             "safe-buffer": "^5.1.2",
             "yallist": "^3.0.0"
@@ -5715,6 +5735,7 @@
         "mkdirp": {
           "version": "0.5.1",
           "bundled": true,
+          "optional": true,
           "requires": {
             "minimist": "0.0.8"
           }
@@ -5787,7 +5808,8 @@
         },
         "number-is-nan": {
           "version": "1.0.1",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "object-assign": {
           "version": "4.1.1",
@@ -5797,6 +5819,7 @@
         "once": {
           "version": "1.4.0",
           "bundled": true,
+          "optional": true,
           "requires": {
             "wrappy": "1"
           }
@@ -5872,7 +5895,8 @@
         },
         "safe-buffer": {
           "version": "5.1.2",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "safer-buffer": {
           "version": "2.1.2",
@@ -5902,6 +5926,7 @@
         "string-width": {
           "version": "1.0.2",
           "bundled": true,
+          "optional": true,
           "requires": {
             "code-point-at": "^1.0.0",
             "is-fullwidth-code-point": "^1.0.0",
@@ -5919,6 +5944,7 @@
         "strip-ansi": {
           "version": "3.0.1",
           "bundled": true,
+          "optional": true,
           "requires": {
             "ansi-regex": "^2.0.0"
           }
@@ -5957,11 +5983,13 @@
         },
         "wrappy": {
           "version": "1.0.2",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         },
         "yallist": {
           "version": "3.0.3",
-          "bundled": true
+          "bundled": true,
+          "optional": true
         }
       }
     },
@@ -6119,7 +6147,8 @@
     "growly": {
       "version": "1.3.0",
       "resolved": "https://registry.npmjs.org/growly/-/growly-1.3.0.tgz",
-      "integrity": "sha1-8QdIy+dq+WS3yWyTxrzCivEgwIE="
+      "integrity": "sha1-8QdIy+dq+WS3yWyTxrzCivEgwIE=",
+      "optional": true
     },
     "gud": {
       "version": "1.0.0",
@@ -6856,6 +6885,7 @@
       "version": "3.3.0",
       "resolved": "https://registry.npmjs.org/inquirer/-/inquirer-3.3.0.tgz",
       "integrity": "sha512-h+xtnyk4EwKvFWHrUYsWErEVR+igKtLdchu+o0Z1RL7VU/jVMFbYir2bp6bAj8efFNxWqHX0dIss6fJQ+/+qeQ==",
+      "optional": true,
       "requires": {
         "ansi-escapes": "^3.0.0",
         "chalk": "^2.0.0",
@@ -6876,12 +6906,14 @@
         "ansi-regex": {
           "version": "3.0.0",
           "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-3.0.0.tgz",
-          "integrity": "sha1-7QMXwyIGT3lGbAKWa922Bas32Zg="
+          "integrity": "sha1-7QMXwyIGT3lGbAKWa922Bas32Zg=",
+          "optional": true
         },
         "strip-ansi": {
           "version": "4.0.0",
           "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-4.0.0.tgz",
           "integrity": "sha1-qEeQIusaw2iocTibY1JixQXuNo8=",
+          "optional": true,
           "requires": {
             "ansi-regex": "^3.0.0"
           }
@@ -7806,6 +7838,7 @@
       "version": "0.51.0",
       "resolved": "https://registry.npmjs.org/metro-react-native-babel-transformer/-/metro-react-native-babel-transformer-0.51.0.tgz",
       "integrity": "sha512-VFnqtE0qrVmU1HV9B04o53+NZHvDwR+CWCoEx4+7vCqJ9Tvas741biqCjah9xtifoKdElQELk6x0soOAWCDFJA==",
+      "optional": true,
       "requires": {
         "@babel/core": "^7.0.0",
         "babel-preset-fbjs": "^3.0.1",
@@ -7817,6 +7850,7 @@
           "version": "0.51.0",
           "resolved": "https://registry.npmjs.org/metro-babel-transformer/-/metro-babel-transformer-0.51.0.tgz",
           "integrity": "sha512-M7KEY/hjD3E8tJEliWgI0VOSaJtqaznC0ItM6FiMrhoGDqqa1BvGofl+EPcKqjBSOV1UgExua/T1VOIWbjwQsw==",
+          "optional": true,
           "requires": {
             "@babel/core": "^7.0.0"
           }
@@ -7825,6 +7859,7 @@
           "version": "0.51.0",
           "resolved": "https://registry.npmjs.org/metro-babel7-plugin-react-transform/-/metro-babel7-plugin-react-transform-0.51.0.tgz",
           "integrity": "sha512-dZ95kXcE2FJMoRsYhxr7YLCbOlHWKwe0bOpihRhfImDTgFfuKIzU4ROQwMUbE0NCbzB+ATFsa2FZ3pHDJ5GI0w==",
+          "optional": true,
           "requires": {
             "@babel/helper-module-imports": "^7.0.0"
           }
@@ -7833,6 +7868,7 @@
           "version": "0.51.0",
           "resolved": "https://registry.npmjs.org/metro-react-native-babel-preset/-/metro-react-native-babel-preset-0.51.0.tgz",
           "integrity": "sha512-Y/aPeLl4RzY8IEAneOyDcpdjto/8yjIuX9eUWRngjSqdHYhGQtqiSBpfTpo0BvXpwNRLwCLHyXo58gNpckTJFw==",
+          "optional": true,
           "requires": {
             "@babel/plugin-proposal-class-properties": "^7.0.0",
             "@babel/plugin-proposal-export-default-from": "^7.0.0",
@@ -8046,6 +8082,7 @@
       "version": "1.9.1",
       "resolved": "https://registry.npmjs.org/morgan/-/morgan-1.9.1.tgz",
       "integrity": "sha512-HQStPIV4y3afTiCYVxirakhlCfGkI161c76kKFca7Fk1JusM//Qeo1ej2XaMniiNeaZklMVrh3vTtIzpzwbpmA==",
+      "optional": true,
       "requires": {
         "basic-auth": "~2.0.0",
         "debug": "2.6.9",
@@ -8231,6 +8268,7 @@
       "version": "5.4.3",
       "resolved": "https://registry.npmjs.org/node-notifier/-/node-notifier-5.4.3.tgz",
       "integrity": "sha512-M4UBGcs4jeOK9CjTsYwkvH6/MzuUmGCyTW+kCY7uO+1ZVr0+FHGdPdIf5CCLqAaxnRrWidyoQlNkMIIVwbKB8Q==",
+      "optional": true,
       "requires": {
         "growly": "^1.3.0",
         "is-wsl": "^1.1.0",
@@ -8490,6 +8528,7 @@
       "version": "3.0.3",
       "resolved": "https://registry.npmjs.org/opn/-/opn-3.0.3.tgz",
       "integrity": "sha1-ttmec5n3jWXDuq/+8fsojpuFJDo=",
+      "optional": true,
       "requires": {
         "object-assign": "^4.0.1"
       }
@@ -8925,6 +8964,7 @@
       "version": "3.0.1",
       "resolved": "https://registry.npmjs.org/plist/-/plist-3.0.1.tgz",
       "integrity": "sha512-GpgvHHocGRyQm74b6FWEZZVRroHKE1I0/BTjAmySaohK+cUn+hZpbqXkc3KWgW3gQYkqcQej35FohcT0FRlkRQ==",
+      "optional": true,
       "requires": {
         "base64-js": "^1.2.3",
         "xmlbuilder": "^9.0.7",
@@ -10196,12 +10236,14 @@
     "rx-lite": {
       "version": "4.0.8",
       "resolved": "https://registry.npmjs.org/rx-lite/-/rx-lite-4.0.8.tgz",
-      "integrity": "sha1-Cx4Rr4vESDbwSmQH6S2kJGe3lEQ="
+      "integrity": "sha1-Cx4Rr4vESDbwSmQH6S2kJGe3lEQ=",
+      "optional": true
     },
     "rx-lite-aggregates": {
       "version": "4.0.8",
       "resolved": "https://registry.npmjs.org/rx-lite-aggregates/-/rx-lite-aggregates-4.0.8.tgz",
       "integrity": "sha1-dTuHqJoRyVRnxKwWJsTvxOBcZ74=",
+      "optional": true,
       "requires": {
         "rx-lite": "*"
       }
@@ -10503,7 +10545,8 @@
     "sax": {
       "version": "1.1.6",
       "resolved": "https://registry.npmjs.org/sax/-/sax-1.1.6.tgz",
-      "integrity": "sha1-XWFr6KXmB9VOEUr65Vt+ry/MMkA="
+      "integrity": "sha1-XWFr6KXmB9VOEUr65Vt+ry/MMkA=",
+      "optional": true
     },
     "scheduler": {
       "version": "0.13.6",
@@ -10698,6 +10741,7 @@
       "version": "1.6.1",
       "resolved": "https://registry.npmjs.org/shell-quote/-/shell-quote-1.6.1.tgz",
       "integrity": "sha1-9HgZSczkAmlxJ0MOo7PFR29IF2c=",
+      "optional": true,
       "requires": {
         "array-filter": "~0.0.0",
         "array-map": "~0.0.0",
@@ -10719,7 +10763,8 @@
     "shellwords": {
       "version": "0.1.1",
       "resolved": "https://registry.npmjs.org/shellwords/-/shellwords-0.1.1.tgz",
-      "integrity": "sha512-vFwSUfQvqybiICwZY5+DAWIPLKsWO31Q91JSKl3UYv+K5c2QRPzn0qzec6QPu1Qc9eHYItiP3NdJqNVqetYAww=="
+      "integrity": "sha512-vFwSUfQvqybiICwZY5+DAWIPLKsWO31Q91JSKl3UYv+K5c2QRPzn0qzec6QPu1Qc9eHYItiP3NdJqNVqetYAww==",
+      "optional": true
     },
     "signal-exit": {
       "version": "3.0.2",
@@ -12863,12 +12908,14 @@
     "xmlbuilder": {
       "version": "9.0.7",
       "resolved": "https://registry.npmjs.org/xmlbuilder/-/xmlbuilder-9.0.7.tgz",
-      "integrity": "sha1-Ey7mPS7FVlxVfiD0wi35rKaGsQ0="
+      "integrity": "sha1-Ey7mPS7FVlxVfiD0wi35rKaGsQ0=",
+      "optional": true
     },
     "xmldoc": {
       "version": "0.4.0",
       "resolved": "https://registry.npmjs.org/xmldoc/-/xmldoc-0.4.0.tgz",
       "integrity": "sha1-0lciS+g5PqrL+DfvIn/Y7CWzaIg=",
+      "optional": true,
       "requires": {
         "sax": "~1.1.1"
       }
@@ -12876,7 +12923,8 @@
     "xmldom": {
       "version": "0.1.27",
       "resolved": "https://registry.npmjs.org/xmldom/-/xmldom-0.1.27.tgz",
-      "integrity": "sha1-1QH5ezvbQDr4757MIFcxh6rawOk="
+      "integrity": "sha1-1QH5ezvbQDr4757MIFcxh6rawOk=",
+      "optional": true
     },
     "xpipe": {
       "version": "1.0.5",