diff --git a/Pipfile b/Pipfile
index 628337b..b467c1d 100644
--- a/Pipfile
+++ b/Pipfile
@@ -6,7 +6,7 @@ verify_ssl = true
 [dev-packages]
 
 [packages]
-vyper = "==0.2.12"
+vyper = "==0.3.0"
 
 [requires]
 python_version = "3.7"
diff --git a/Pipfile.lock b/Pipfile.lock
index d1cd00e..d9f5fb1 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "da8ad20de54f163be00f924d47d392cd3ec65dc63998a782f3f4fa818b65391e"
+            "sha256": "f26da07ec8650d6f1a9c99a760f1420019ab94eac5ab3b4d4c39334ecc1eb116"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -23,46 +23,56 @@
             ],
             "version": "==2.0.4"
         },
+        "cached-property": {
+            "hashes": [
+                "sha256:9fa5755838eecbb2d234c3aa390bd80fbd3ac6b6869109bfc1b499f7bd89a130",
+                "sha256:df4f613cf7ad9a588cc381aaf4a512d26265ecebd5eb9e1ba12f1319eb85a6a0"
+            ],
+            "markers": "python_version < '3.8'",
+            "version": "==1.5.2"
+        },
         "pycryptodome": {
             "hashes": [
-                "sha256:09c1555a3fa450e7eaca41ea11cd00afe7c91fef52353488e65663777d8524e0",
-                "sha256:12222a5edc9ca4a29de15fbd5339099c4c26c56e13c2ceddf0b920794f26165d",
-                "sha256:1723ebee5561628ce96748501cdaa7afaa67329d753933296321f0be55358dce",
-                "sha256:1c5e1ca507de2ad93474be5cfe2bfa76b7cf039a1a32fc196f40935944871a06",
-                "sha256:2603c98ae04aac675fefcf71a6c87dc4bb74a75e9071ae3923bbc91a59f08d35",
-                "sha256:2dea65df54349cdfa43d6b2e8edb83f5f8d6861e5cf7b1fbc3e34c5694c85e27",
-                "sha256:31c1df17b3dc5f39600a4057d7db53ac372f492c955b9b75dd439f5d8b460129",
-                "sha256:38661348ecb71476037f1e1f553159b80d256c00f6c0b00502acac891f7116d9",
-                "sha256:3e2e3a06580c5f190df843cdb90ea28d61099cf4924334d5297a995de68e4673",
-                "sha256:3f840c49d38986f6e17dbc0673d37947c88bc9d2d9dba1c01b979b36f8447db1",
-                "sha256:501ab36aae360e31d0ec370cf5ce8ace6cb4112060d099b993bc02b36ac83fb6",
-                "sha256:60386d1d4cfaad299803b45a5bc2089696eaf6cdd56f9fc17479a6f89595cfc8",
-                "sha256:6260e24d41149268122dd39d4ebd5941e9d107f49463f7e071fd397e29923b0c",
-                "sha256:6bbf7fee7b7948b29d7e71fcacf48bac0c57fb41332007061a933f2d996f9713",
-                "sha256:6d2df5223b12437e644ce0a3be7809471ffa71de44ccd28b02180401982594a6",
-                "sha256:758949ca62690b1540dfb24ad773c6da9cd0e425189e83e39c038bbd52b8e438",
-                "sha256:77997519d8eb8a4adcd9a47b9cec18f9b323e296986528186c0e9a7a15d6a07e",
-                "sha256:7fd519b89585abf57bf47d90166903ec7b43af4fe23c92273ea09e6336af5c07",
-                "sha256:98213ac2b18dc1969a47bc65a79a8fca02a414249d0c8635abb081c7f38c91b6",
-                "sha256:99b2f3fc51d308286071d0953f92055504a6ffe829a832a9fc7a04318a7683dd",
-                "sha256:9b6f711b25e01931f1c61ce0115245a23cdc8b80bf8539ac0363bdcf27d649b6",
-                "sha256:a3105a0eb63eacf98c2ecb0eb4aa03f77f40fbac2bdde22020bb8a536b226bb8",
-                "sha256:a8eb8b6ea09ec1c2535bf39914377bc8abcab2c7d30fa9225eb4fe412024e427",
-                "sha256:a92d5c414e8ee1249e850789052608f582416e82422502dc0ac8c577808a9067",
-                "sha256:d3d6958d53ad307df5e8469cc44474a75393a434addf20ecd451f38a72fe29b8",
-                "sha256:e0a4d5933a88a2c98bbe19c0c722f5483dc628d7a38338ac2cb64a7dbd34064b",
-                "sha256:e3bf558c6aeb49afa9f0c06cee7fb5947ee5a1ff3bd794b653d39926b49077fa",
-                "sha256:e61e363d9a5d7916f3a4ce984a929514c0df3daf3b1b2eb5e6edbb131ee771cf",
-                "sha256:f977cdf725b20f6b8229b0c87acb98c7717e742ef9f46b113985303ae12a99da",
-                "sha256:fc7489a50323a0df02378bc2fff86eb69d94cc5639914346c736be981c6a02e7"
+                "sha256:04e14c732c3693d2830839feed5129286ce47ffa8bfe90e4ae042c773e51c677",
+                "sha256:11d3164fb49fdee000fde05baecce103c0c698168ef1a18d9c7429dd66f0f5bb",
+                "sha256:217dcc0c92503f7dd4b3d3b7d974331a4419f97f555c99a845c3b366fed7056b",
+                "sha256:24c1b7705d19d8ae3e7255431efd2e526006855df62620118dd7b5374c6372f6",
+                "sha256:309529d2526f3fb47102aeef376b3459110a6af7efb162e860b32e3a17a46f06",
+                "sha256:3a153658d97258ca20bf18f7fe31c09cc7c558b6f8974a6ec74e19f6c634bd64",
+                "sha256:3f9fb499e267039262569d08658132c9cd8b136bf1d8c56b72f70ed05551e526",
+                "sha256:3faa6ebd35c61718f3f8862569c1f38450c24f3ededb213e1a64806f02f584bc",
+                "sha256:40083b0d7f277452c7f2dd4841801f058cc12a74c219ee4110d65774c6a58bef",
+                "sha256:49e54f2245befb0193848c8c8031d8d1358ed4af5a1ae8d0a3ba669a5cdd3a72",
+                "sha256:4e8fc4c48365ce8a542fe48bf1360da05bb2851df12f64fc94d751705e7cdbe7",
+                "sha256:54d4e4d45f349d8c4e2f31c2734637ff62a844af391b833f789da88e43a8f338",
+                "sha256:66301e4c42dee43ee2da256625d3fe81ef98cc9924c2bd535008cc3ad8ded77b",
+                "sha256:6b45fcace5a5d9c57ba87cf804b161adc62aa826295ce7f7acbcbdc0df74ed37",
+                "sha256:7efec2418e9746ec48e264eea431f8e422d931f71c57b1c96ee202b117f58fa9",
+                "sha256:851e6d4930b160417235955322db44adbdb19589918670d63f4acd5d92959ac0",
+                "sha256:8e82524e7c354033508891405574d12e612cc4fdd3b55d2c238fc1a3e300b606",
+                "sha256:8ec154ec445412df31acf0096e7f715e30e167c8f2318b8f5b1ab7c28f4c82f7",
+                "sha256:91ba4215a1f37d0f371fe43bc88c5ff49c274849f3868321c889313787de7672",
+                "sha256:97e7df67a4da2e3f60612bbfd6c3f243a63a15d8f4797dd275e1d7b44a65cb12",
+                "sha256:9a2312440057bf29b9582f72f14d79692044e63bfbc4b4bbea8559355f44f3dd",
+                "sha256:a7471646d8cd1a58bb696d667dcb3853e5c9b341b68dcf3c3cc0893d0f98ca5f",
+                "sha256:ac3012c36633564b2b5539bb7c6d9175f31d2ce74844e9abe654c428f02d0fd8",
+                "sha256:b1daf251395af7336ddde6a0015ba5e632c18fe646ba930ef87402537358e3b4",
+                "sha256:b217b4525e60e1af552d62bec01b4685095436d4de5ecde0f05d75b2f95ba6d4",
+                "sha256:c61ea053bd5d4c12a063d7e704fbe1c45abb5d2510dab55bd95d166ba661604f",
+                "sha256:c6469d1453f5864e3321a172b0aa671b938d753cbf2376b99fa2ab8841539bb8",
+                "sha256:cefe6b267b8e5c3c72e11adec35a9c7285b62e8ea141b63e87055e9a9e5f2f8c",
+                "sha256:d713dc0910e5ded07852a05e9b75f1dd9d3a31895eebee0668f612779b2a748c",
+                "sha256:db15fa07d2a4c00beeb5e9acdfdbc1c79f9ccfbdc1a8f36c82c4aa44951b33c9"
             ],
-            "version": "==3.10.1"
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3, 3.4'",
+            "version": "==3.10.4"
         },
         "semantic-version": {
             "hashes": [
                 "sha256:45e4b32ee9d6d70ba5f440ec8cc5221074c7f4b0e8918bdab748cc37912440a9",
                 "sha256:d2cb2de0558762934679b9a104e82eca7af448c9f4974d1f3eeccff651df8a54"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==2.8.5"
         },
         "six": {
@@ -70,15 +80,16 @@
                 "sha256:1e61c37477a1626458e36f7b1d82aa5c9b094fa4802892072e49de9c60c4c926",
                 "sha256:8abb2f1d86890a2dfb989f9a77cfcfd3e47c2a354b01111771326f8aa26e0254"
             ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
             "version": "==1.16.0"
         },
         "vyper": {
             "hashes": [
-                "sha256:c97dd2d2c9ed5185338c8d9c78ad00432873fbe3387db62ecf7e33bf4e33882a",
-                "sha256:caad7d03a1e69b80d6cd6711d1fb810df91d13e2cbced52a606a0bbb476af31e"
+                "sha256:2e36910faef0776e76a99fa9aa6c0b7d50cb15f67bf0313763de415dcab2c6c2",
+                "sha256:3e50cd802696ea3f5e6ab1bf4c9a90a39c332591d416c99f3d2fa93d7d7ba394"
             ],
             "index": "pypi",
-            "version": "==0.2.12"
+            "version": "==0.3.0"
         }
     },
     "develop": {}