diff --git a/Pipfile b/Pipfile
index 1bd8a18..1716b3c 100644
--- a/Pipfile
+++ b/Pipfile
@@ -7,7 +7,7 @@ name = "pypi"
 
 [packages]
 
-py = "==1.4.31"
+py = "==1.10.0"
 pytest = "==2.8.7"
 "pytest-cov" = "==2.2.0"
 "pytest-random" = "==0.2"
diff --git a/Pipfile.lock b/Pipfile.lock
index 4b6ac21..b9be0b2 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,20 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "65c8f60062b296ec71254432b62e66cffa46e7069031ec393e5505b428587c85"
-        },
-        "host-environment-markers": {
-            "implementation_name": "cpython",
-            "implementation_version": "3.5.2",
-            "os_name": "posix",
-            "platform_machine": "x86_64",
-            "platform_python_implementation": "CPython",
-            "platform_release": "4.4.0-96-generic",
-            "platform_system": "Linux",
-            "platform_version": "#119-Ubuntu SMP Tue Sep 12 14:59:54 UTC 2017",
-            "python_full_version": "3.5.2",
-            "python_version": "3.5",
-            "sys_platform": "linux"
+            "sha256": "db87c25d0e1fb6e20a2b5490ee23482b92e630b80821dbcf54f28148eb4c4363"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -31,78 +18,90 @@
     "default": {
         "coverage": {
             "hashes": [
-                "sha256:c1456f66c536010cf9e4633a8853a9153e8fd588393695295afd4d0fc16c1d74",
-                "sha256:97a7ec51cdde3a386e390b159b20f247ccb478084d925c75f1faa3d26c01335e",
-                "sha256:83e955b975666b5a07d217135e7797857ce844eb340a99e46cc25525120417c4",
-                "sha256:483ed14080c5301048128bb027b77978c632dd9e92e3ecb09b7e28f5b92abfcf",
-                "sha256:ef574ab9640bcfa2f3c671831faf03f65788945fdf8efa4d4a1fffc034838e2a",
-                "sha256:c5a205b4da3c624f5119dc4d84240789b5906bb8468902ec22dcc4aad8aa4638",
-                "sha256:5dea90ed140e7fa9bc00463313f9bc4a6e6aff297b4969615e7a688615c4c4d2",
-                "sha256:f9e83b39d29c2815a38e4118d776b482d4082b5bf9c9147fbc99a3f83abe480a",
-                "sha256:700040c354f0230287906b1276635552a3def4b646e0145555bc9e2e5da9e365",
-                "sha256:7f1eacae700c66c3d7362a433b228599c9d94a5a3a52613dddd9474e04deb6bc",
-                "sha256:13ef9f799c8fb45c446a239df68034de3a6f3de274881b088bebd7f5661f79f8",
-                "sha256:dfb011587e2b7299112f08a2a60d2601706aac9abde37aa1177ea825adaed923",
-                "sha256:381be5d31d3f0d912334cf2c159bc7bea6bfe6b0e3df6061a3bf2bf88359b1f6",
-                "sha256:83a477ac4f55a6ef59552683a0544d47b68a85ce6a80fd0ca6b3dc767f6495fb",
-                "sha256:dfd35f1979da31bcabbe27bcf78d4284d69870731874af629082590023a77336",
-                "sha256:9681efc2d310cfc53863cc6f63e88ebe7a48124550fa822147996cb09390b6ab",
-                "sha256:53770b20ac5b4a12e99229d4bae57af0945be87cc257fce6c6c7571a39f0c5d4",
-                "sha256:8801880d32f11b6df11c32a961e186774b4634ae39d7c43235f5a24368a85f07",
-                "sha256:16db2c69a1acbcb3c13211e9f954e22b22a729909d81f983b6b9badacc466eda",
-                "sha256:ef43a06a960b46c73c018704051e023ee6082030f145841ffafc8728039d5a88",
-                "sha256:c3e2736664a6074fc9bd54fb643f5af0fc60bfedb2963b3d3f98c7450335e34c",
-                "sha256:17709e22e4c9f5412ba90f446fb13b245cc20bf4a60377021bbff6c0f1f63e7c",
-                "sha256:a2f7106d1167825c4115794c2ba57cc3b15feb6183db5328fa66f94c12902d8b",
-                "sha256:2a08e978f402696c6956eee9d1b7e95d3ad042959b71bafe1f3e4557cbd6e0ac",
-                "sha256:57f510bb16efaec0b6f371b64a8000c62e7e3b3e48e8b0a5745ade078d849814",
-                "sha256:0f1883eab9c19aa243f51308751b8a2a547b9b817b721cc0ecf3efb99fafbea7",
-                "sha256:e00fe141e22ce6e9395aa24d862039eb180c6b7e89df0bbaf9765e9aebe560a9",
-                "sha256:ec596e4401553caa6dd2e3349ce47f9ef82c1f1bcba5d8ac3342724f0df8d6ff",
-                "sha256:c820a533a943ebc860acc0ce6a00dd36e0fdf2c6f619ff8225755169428c5fa2",
-                "sha256:b7f7283eb7badd2b8a9c6a9d6eeca200a0a24db6be79baee2c11398f978edcaa",
-                "sha256:a5ed27ad3e8420b2d6b625dcbd3e59488c14ccc06030167bcf14ffb0f4189b77",
-                "sha256:d7b70b7b4eb14d0753d33253fe4f121ca99102612e2719f0993607deb30c6f33",
-                "sha256:4047dc83773869701bde934fb3c4792648eda7c0e008a77a0aec64157d246801",
-                "sha256:7a9c44400ee0f3b4546066e0710e1250fd75831adc02ab99dda176ad8726f424",
-                "sha256:0f649e68db74b1b5b8ca4161d08eb2b8fa8ae11af1ebfb80e80e112eb0ef5300",
-                "sha256:52964fae0fafef8bd283ad8e9a9665205a9fdf912535434defc0ec3def1da26b",
-                "sha256:36aa6c8db83bc27346ddcd8c2a60846a7178ecd702672689d3ea1828eb1a4d11",
-                "sha256:9824e15b387d331c0fc0fef905a539ab69784368a1d6ac3db864b4182e520948",
-                "sha256:4a678e1b9619a29c51301af61ab84122e2f8cc7a0a6b40854b808ac6be604300",
-                "sha256:8bb7c8dca54109b61013bc4114d96effbf10dea136722c586bce3a5d9fc4e730",
-                "sha256:1a41d621aa9b6ab6457b557a754d50aaff0813fad3453434de075496fca8a183",
-                "sha256:0fa423599fc3d9e18177f913552cdb34a8d9ad33efcf52a98c9d4b644edb42c5",
-                "sha256:e61a4ba0b2686040cb4828297c7e37bcaf3a1a1c0bc0dbe46cc789dde51a80fa",
-                "sha256:ce9ef0fc99d11d418662e36fd8de6d71b19ec87c2eab961a117cc9d087576e72"
+                "sha256:004d1880bed2d97151facef49f08e255a20ceb6f9432df75f4eef018fdd5a78c",
+                "sha256:01d84219b5cdbfc8122223b39a954820929497a1cb1422824bb86b07b74594b6",
+                "sha256:040af6c32813fa3eae5305d53f18875bedd079960822ef8ec067a66dd8afcd45",
+                "sha256:06191eb60f8d8a5bc046f3799f8a07a2d7aefb9504b0209aff0b47298333302a",
+                "sha256:13034c4409db851670bc9acd836243aeee299949bd5673e11844befcb0149f03",
+                "sha256:13c4ee887eca0f4c5a247b75398d4114c37882658300e153113dafb1d76de529",
+                "sha256:184a47bbe0aa6400ed2d41d8e9ed868b8205046518c52464fde713ea06e3a74a",
+                "sha256:18ba8bbede96a2c3dde7b868de9dcbd55670690af0988713f0603f037848418a",
+                "sha256:1aa846f56c3d49205c952d8318e76ccc2ae23303351d9270ab220004c580cfe2",
+                "sha256:217658ec7187497e3f3ebd901afdca1af062b42cfe3e0dafea4cced3983739f6",
+                "sha256:24d4a7de75446be83244eabbff746d66b9240ae020ced65d060815fac3423759",
+                "sha256:2910f4d36a6a9b4214bb7038d537f015346f413a975d57ca6b43bf23d6563b53",
+                "sha256:2949cad1c5208b8298d5686d5a85b66aae46d73eec2c3e08c817dd3513e5848a",
+                "sha256:2a3859cb82dcbda1cfd3e6f71c27081d18aa251d20a17d87d26d4cd216fb0af4",
+                "sha256:2cafbbb3af0733db200c9b5f798d18953b1a304d3f86a938367de1567f4b5bff",
+                "sha256:2e0d881ad471768bf6e6c2bf905d183543f10098e3b3640fc029509530091502",
+                "sha256:30c77c1dc9f253283e34c27935fded5015f7d1abe83bc7821680ac444eaf7793",
+                "sha256:3487286bc29a5aa4b93a072e9592f22254291ce96a9fbc5251f566b6b7343cdb",
+                "sha256:372da284cfd642d8e08ef606917846fa2ee350f64994bebfbd3afb0040436905",
+                "sha256:41179b8a845742d1eb60449bdb2992196e211341818565abded11cfa90efb821",
+                "sha256:44d654437b8ddd9eee7d1eaee28b7219bec228520ff809af170488fd2fed3e2b",
+                "sha256:4a7697d8cb0f27399b0e393c0b90f0f1e40c82023ea4d45d22bce7032a5d7b81",
+                "sha256:51cb9476a3987c8967ebab3f0fe144819781fca264f57f89760037a2ea191cb0",
+                "sha256:52596d3d0e8bdf3af43db3e9ba8dcdaac724ba7b5ca3f6358529d56f7a166f8b",
+                "sha256:53194af30d5bad77fcba80e23a1441c71abfb3e01192034f8246e0d8f99528f3",
+                "sha256:5fec2d43a2cc6965edc0bb9e83e1e4b557f76f843a77a2496cbe719583ce8184",
+                "sha256:6c90e11318f0d3c436a42409f2749ee1a115cd8b067d7f14c148f1ce5574d701",
+                "sha256:74d881fc777ebb11c63736622b60cb9e4aee5cace591ce274fb69e582a12a61a",
+                "sha256:7501140f755b725495941b43347ba8a2777407fc7f250d4f5a7d2a1050ba8e82",
+                "sha256:796c9c3c79747146ebd278dbe1e5c5c05dd6b10cc3bcb8389dfdf844f3ead638",
+                "sha256:869a64f53488f40fa5b5b9dcb9e9b2962a66a87dab37790f3fcfb5144b996ef5",
+                "sha256:8963a499849a1fc54b35b1c9f162f4108017b2e6db2c46c1bed93a72262ed083",
+                "sha256:8d0a0725ad7c1a0bcd8d1b437e191107d457e2ec1084b9f190630a4fb1af78e6",
+                "sha256:900fbf7759501bc7807fd6638c947d7a831fc9fdf742dc10f02956ff7220fa90",
+                "sha256:92b017ce34b68a7d67bd6d117e6d443a9bf63a2ecf8567bb3d8c6c7bc5014465",
+                "sha256:970284a88b99673ccb2e4e334cfb38a10aab7cd44f7457564d11898a74b62d0a",
+                "sha256:972c85d205b51e30e59525694670de6a8a89691186012535f9d7dbaa230e42c3",
+                "sha256:9a1ef3b66e38ef8618ce5fdc7bea3d9f45f3624e2a66295eea5e57966c85909e",
+                "sha256:af0e781009aaf59e25c5a678122391cb0f345ac0ec272c7961dc5455e1c40066",
+                "sha256:b6d534e4b2ab35c9f93f46229363e17f63c53ad01330df9f2d6bd1187e5eaacf",
+                "sha256:b7895207b4c843c76a25ab8c1e866261bcfe27bfaa20c192de5190121770672b",
+                "sha256:c0891a6a97b09c1f3e073a890514d5012eb256845c451bd48f7968ef939bf4ae",
+                "sha256:c2723d347ab06e7ddad1a58b2a821218239249a9e4365eaff6649d31180c1669",
+                "sha256:d1f8bf7b90ba55699b3a5e44930e93ff0189aa27186e96071fac7dd0d06a1873",
+                "sha256:d1f9ce122f83b2305592c11d64f181b87153fc2c2bbd3bb4a3dde8303cfb1a6b",
+                "sha256:d314ed732c25d29775e84a960c3c60808b682c08d86602ec2c3008e1202e3bb6",
+                "sha256:d636598c8305e1f90b439dbf4f66437de4a5e3c31fdf47ad29542478c8508bbb",
+                "sha256:deee1077aae10d8fa88cb02c845cfba9b62c55e1183f52f6ae6a2df6a2187160",
+                "sha256:ebe78fe9a0e874362175b02371bdfbee64d8edc42a044253ddf4ee7d3c15212c",
+                "sha256:f030f8873312a16414c0d8e1a1ddff2d3235655a2174e3648b4fa66b3f2f1079",
+                "sha256:f0b278ce10936db1a37e6954e15a3730bea96a0997c26d7fee88e6c396c2086d",
+                "sha256:f11642dddbb0253cc8853254301b51390ba0081750a8ac03f20ea8103f0c56b6"
             ],
-            "version": "==4.4.1"
+            "version": "==5.5"
         },
         "py": {
             "hashes": [
-                "sha256:4a3e4f3000c123835ac39cab5ccc510642153bc47bc1f13e2bbb53039540ae69",
-                "sha256:a6501963c725fc2554dabfece8ae9a8fb5e149c0ac0a42fd2b02c5c1c57fc114"
+                "sha256:21b81bda15b66ef5e1a777a21c4dcd9c20ad3efd0b3f817e7a809035269e1bd3",
+                "sha256:3b80836aa6d1feeaa108e046da6423ab8f6ceda6468545ae8d02d9d58d18818a"
             ],
-            "version": "==1.4.31"
+            "index": "pypi",
+            "version": "==1.10.0"
         },
         "pytest": {
             "hashes": [
                 "sha256:33612ed6de42f05640fe058aafdf08899eabcb210da74aeb0b788de9695c8bb5",
                 "sha256:fc4c86be54fce08e4b85b646a736efa18c6cde7599c1d2919f4f74629e018baf"
             ],
+            "index": "pypi",
             "version": "==2.8.7"
         },
         "pytest-cov": {
             "hashes": [
-                "sha256:eec35bb0ef2a7dbe958f50b667403ab4abad53a17cc4f1a585b2aabac6f68088",
-                "sha256:2231d43f07760d6904dadceabca53ab16ef95ba58fff393861b64c0cab96c9d1"
+                "sha256:2231d43f07760d6904dadceabca53ab16ef95ba58fff393861b64c0cab96c9d1",
+                "sha256:eec35bb0ef2a7dbe958f50b667403ab4abad53a17cc4f1a585b2aabac6f68088"
             ],
+            "index": "pypi",
             "version": "==2.2.0"
         },
         "pytest-random": {
             "hashes": [
                 "sha256:92f25db8c5d9ffc20d90b51997b914372d6955cb9cf1f6ead45b90514fc0eddd"
             ],
+            "index": "pypi",
             "version": "==0.2"
         }
     },