Update prettier config

package-lock.json

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       "dev": true,
       "requires": {
-        "balanced-match": "1.0.0",
+        "balanced-match": "^1.0.0",
         "concat-map": "0.0.1"
       }
     },
       "integrity": "sha1-g6c/L+pWmJj7c3GTyPhzyvbUXJQ=",
       "dev": true,
       "requires": {
-        "foreach": "2.0.5",
-        "object-keys": "1.0.11"
+        "foreach": "^2.0.5",
+        "object-keys": "^1.0.8"
       }
     },
     "defined": {
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       "dev": true,
       "requires": {
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-        "function-bind": "1.1.1",
-        "has": "1.0.1",
-        "is-callable": "1.1.3",
-        "is-regex": "1.0.4"
+        "es-to-primitive": "^1.1.1",
+        "function-bind": "^1.1.1",
+        "has": "^1.0.1",
+        "is-callable": "^1.1.3",
+        "is-regex": "^1.0.4"
       }
     },
     "es-to-primitive": {
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       "dev": true,
       "requires": {
-        "is-callable": "1.1.3",
-        "is-date-object": "1.0.1",
-        "is-symbol": "1.0.1"
+        "is-callable": "^1.1.1",
+        "is-date-object": "^1.0.1",
+        "is-symbol": "^1.0.1"
       }
     },
     "faucet": {
       "dev": true,
       "requires": {
         "defined": "0.0.0",
-        "duplexer": "0.1.1",
+        "duplexer": "~0.1.1",
         "minimist": "0.0.5",
-        "sprintf": "0.1.5",
-        "tap-parser": "0.4.3",
-        "tape": "2.3.3",
-        "through2": "0.2.3"
+        "sprintf": "~0.1.3",
+        "tap-parser": "~0.4.0",
+        "tape": "~2.3.2",
+        "through2": "~0.2.3"
       },
       "dependencies": {
         "deep-equal": {
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           "dev": true,
           "requires": {
-            "deep-equal": "0.1.2",
-            "defined": "0.0.0",
-            "inherits": "2.0.3",
-            "jsonify": "0.0.0",
-            "resumer": "0.0.0",
-            "through": "2.3.8"
+            "deep-equal": "~0.1.0",
+            "defined": "~0.0.0",
+            "inherits": "~2.0.1",
+            "jsonify": "~0.0.0",
+            "resumer": "~0.0.0",
+            "through": "~2.3.4"
           }
         }
       }
       "integrity": "sha1-LEBFC5NI6X8oEyJZO6lnBLmr1NQ=",
       "dev": true,
       "requires": {
-        "is-function": "1.0.1"
+        "is-function": "~1.0.0"
       }
     },
     "foreach": {
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       "dev": true,
       "requires": {
-        "fs.realpath": "1.0.0",
-        "inflight": "1.0.6",
-        "inherits": "2.0.3",
-        "minimatch": "3.0.4",
-        "once": "1.4.0",
-        "path-is-absolute": "1.0.1"
+        "fs.realpath": "^1.0.0",
+        "inflight": "^1.0.4",
+        "inherits": "2",
+        "minimatch": "^3.0.4",
+        "once": "^1.3.0",
+        "path-is-absolute": "^1.0.0"
       }
     },
     "has": {
       "integrity": "sha1-hGFzP1OLCDfJNh45qauelwTcLyg=",
       "dev": true,
       "requires": {
-        "function-bind": "1.1.1"
+        "function-bind": "^1.0.2"
       }
     },
     "inflight": {
       "integrity": "sha1-Sb1jMdfQLQwJvJEKEHW6gWW1bfk=",
       "dev": true,
       "requires": {
-        "once": "1.4.0",
-        "wrappy": "1.0.2"
+        "once": "^1.3.0",
+        "wrappy": "1"
       }
     },
     "inherits": {
       "integrity": "sha1-VRdIm1RwkbCTDglWVM7SXul+lJE=",
       "dev": true,
       "requires": {
-        "has": "1.0.1"
+        "has": "^1.0.1"
       }
     },
     "is-symbol": {
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       "dev": true,
       "requires": {
-        "brace-expansion": "1.1.11"
+        "brace-expansion": "^1.1.7"
       }
     },
     "minimist": {
       "integrity": "sha1-WDsap3WWHUsROsF9nFC6753Xa9E=",
       "dev": true,
       "requires": {
-        "wrappy": "1.0.2"
+        "wrappy": "1"
       }
     },
     "path-is-absolute": {
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       "dev": true,
       "requires": {
-        "core-util-is": "1.0.2",
-        "inherits": "2.0.3",
+        "core-util-is": "~1.0.0",
+        "inherits": "~2.0.1",
         "isarray": "0.0.1",
-        "string_decoder": "0.10.31"
+        "string_decoder": "~0.10.x"
       }
     },
     "resolve": {
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       "dev": true,
       "requires": {
-        "path-parse": "1.0.5"
+        "path-parse": "^1.0.5"
       }
     },
     "resumer": {
       "integrity": "sha1-8ej0YeQGS6Oegq883CqMiT0HZ1k=",
       "dev": true,
       "requires": {
-        "through": "2.3.8"
+        "through": "~2.3.4"
       }
     },
     "sprintf": {
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       "dev": true,
       "requires": {
-        "define-properties": "1.1.2",
-        "es-abstract": "1.11.0",
-        "function-bind": "1.1.1"
+        "define-properties": "^1.1.2",
+        "es-abstract": "^1.5.0",
+        "function-bind": "^1.0.2"
       }
     },
     "string_decoder": {
       "integrity": "sha1-pOrhkMENdsehEZIf84u+TVjwnuo=",
       "dev": true,
       "requires": {
-        "inherits": "2.0.3",
-        "readable-stream": "1.1.14"
+        "inherits": "~2.0.1",
+        "readable-stream": "~1.1.11"
       }
     },
     "tape": {
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       "dev": true,
       "requires": {
-        "deep-equal": "1.0.1",
-        "defined": "1.0.0",
-        "for-each": "0.3.2",
-        "function-bind": "1.1.1",
-        "glob": "7.1.2",
-        "has": "1.0.1",
-        "inherits": "2.0.3",
-        "minimist": "1.2.0",
-        "object-inspect": "1.5.0",
-        "resolve": "1.5.0",
-        "resumer": "0.0.0",
-        "string.prototype.trim": "1.1.2",
-        "through": "2.3.8"
+        "deep-equal": "~1.0.1",
+        "defined": "~1.0.0",
+        "for-each": "~0.3.2",
+        "function-bind": "~1.1.1",
+        "glob": "~7.1.2",
+        "has": "~1.0.1",
+        "inherits": "~2.0.3",
+        "minimist": "~1.2.0",
+        "object-inspect": "~1.5.0",
+        "resolve": "~1.5.0",
+        "resumer": "~0.0.0",
+        "string.prototype.trim": "~1.1.2",
+        "through": "~2.3.8"
       }
     },
     "through": {
       "integrity": "sha1-6zKE2k6jEbbMis42U3SKUqvyWj8=",
       "dev": true,
       "requires": {
-        "readable-stream": "1.1.14",
-        "xtend": "2.1.2"
+        "readable-stream": "~1.1.9",
+        "xtend": "~2.1.1"
       }
     },
     "wrappy": {
       "integrity": "sha1-bv7MKk2tjmlixJAbM3znuoe10os=",
       "dev": true,
       "requires": {
-        "object-keys": "0.4.0"
+        "object-keys": "~0.4.0"
       },
       "dependencies": {
         "object-keys": {

package.json

   "main": "index.js",
   "scripts": {
     "test": "faucet test/*.js",
-    "pretty": "prettier --single-quote --no-semi --trailing-comma all --write ./**/*.js"
+    "pretty": "prettier --single-quote --no-semi --trailing-comma all --arrow-parens avoid --write ./**/*.js"
   },
   "keywords": [],
   "author": "",