diff --git a/package-lock.json b/package-lock.json
index c34fb8c..7c0fb1f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -715,8 +715,15 @@
     "@types/chai": {
       "version": "4.2.11",
       "resolved": "https://registry.npmjs.org/@types/chai/-/chai-4.2.11.tgz",
-      "integrity": "sha512-t7uW6eFafjO+qJ3BIV2gGUyZs27egcNRkUdalkud+Qa3+kg//f129iuOFivHDXQ+vnU3fDXuwgv0cqMCbcE8sw==",
-      "dev": true
+      "integrity": "sha512-t7uW6eFafjO+qJ3BIV2gGUyZs27egcNRkUdalkud+Qa3+kg//f129iuOFivHDXQ+vnU3fDXuwgv0cqMCbcE8sw=="
+    },
+    "@types/chai-spies": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/@types/chai-spies/-/chai-spies-1.0.1.tgz",
+      "integrity": "sha512-vvlTzisMpzmPZaKDd0pFybCJB5bzx398JEdPsVD9Rwq4a7dcGSUDlNG2PAVhsanRBPl4hezqnlaFtL1/YwBGgw==",
+      "requires": {
+        "@types/chai": "*"
+      }
     },
     "@types/color-name": {
       "version": "1.1.1",
@@ -953,6 +960,12 @@
       "integrity": "sha512-tsFzPpcttalNjFBCFMqsKYQcWxxen1pgJR56by//QwvJc4/OUS3kPOOttx2tSIfjsylB0pYu7f5D3K1RCxUnUg==",
       "dev": true
     },
+    "abbrev": {
+      "version": "1.0.9",
+      "resolved": "https://registry.npmjs.org/abbrev/-/abbrev-1.0.9.tgz",
+      "integrity": "sha1-kbR5JYinc4wl813W9jdSovh3YTU=",
+      "dev": true
+    },
     "acorn": {
       "version": "7.1.1",
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-7.1.1.tgz",
@@ -1018,6 +1031,13 @@
       "resolved": "https://registry.npmjs.org/ajv-keywords/-/ajv-keywords-3.4.1.tgz",
       "integrity": "sha512-RO1ibKvd27e6FEShVFfPALuHI3WjSVNeK5FIsmme/LYRNxjKuNj+Dt7bucLa6NdSv3JcVTyMlm9kGR84z1XpaQ=="
     },
+    "amdefine": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/amdefine/-/amdefine-1.0.1.tgz",
+      "integrity": "sha1-SlKCrBZHKek2Gbz9OtFR+BfOkfU=",
+      "dev": true,
+      "optional": true
+    },
     "ansi-colors": {
       "version": "3.2.3",
       "resolved": "https://registry.npmjs.org/ansi-colors/-/ansi-colors-3.2.3.tgz",
@@ -1247,6 +1267,12 @@
       "resolved": "https://registry.npmjs.org/astral-regex/-/astral-regex-1.0.0.tgz",
       "integrity": "sha512-+Ryf6g3BKoRc7jfp7ad8tM4TtMiaWvbF/1/sQcZPkkS7ag3D5nMBCe2UfOTONtAkaG0tO0ij3C5Lwmf1EiyjHg=="
     },
+    "async": {
+      "version": "1.5.2",
+      "resolved": "https://registry.npmjs.org/async/-/async-1.5.2.tgz",
+      "integrity": "sha1-7GphrlZIDAw8skHJVhjiCJL5Zyo=",
+      "dev": true
+    },
     "async-each": {
       "version": "1.0.3",
       "resolved": "https://registry.npmjs.org/async-each/-/async-each-1.0.3.tgz",
@@ -1681,6 +1707,12 @@
         "type-detect": "^4.0.5"
       }
     },
+    "chai-spies": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/chai-spies/-/chai-spies-1.0.0.tgz",
+      "integrity": "sha512-elF2ZUczBsFoP07qCfMO/zeggs8pqCf3fZGyK5+2X4AndS8jycZYID91ztD9oQ7d/0tnS963dPkd0frQEThDsg==",
+      "dev": true
+    },
     "chalk": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/chalk/-/chalk-3.0.0.tgz",
@@ -2063,6 +2095,19 @@
       "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.2.tgz",
       "integrity": "sha1-tf1UIgqivFq1eqtxQMlAdUUDwac="
     },
+    "coveralls": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/coveralls/-/coveralls-3.1.0.tgz",
+      "integrity": "sha512-sHxOu2ELzW8/NC1UP5XVLbZDzO4S3VxfFye3XYCznopHy02YjNkHcj5bKaVw2O7hVaBdBjEdQGpie4II1mWhuQ==",
+      "dev": true,
+      "requires": {
+        "js-yaml": "^3.13.1",
+        "lcov-parse": "^1.0.0",
+        "log-driver": "^1.2.7",
+        "minimist": "^1.2.5",
+        "request": "^2.88.2"
+      }
+    },
     "create-ecdh": {
       "version": "4.0.3",
       "resolved": "https://registry.npmjs.org/create-ecdh/-/create-ecdh-4.0.3.tgz",
@@ -2353,9 +2398,9 @@
       }
     },
     "elliptic": {
-      "version": "6.5.2",
-      "resolved": "https://registry.npmjs.org/elliptic/-/elliptic-6.5.2.tgz",
-      "integrity": "sha512-f4x70okzZbIQl/NSRLkI/+tteV/9WqL98zx+SQ69KbXxmVrmjwsNUPn/gYJJ0sHvEak24cZgHIPegRePAtA/xw==",
+      "version": "6.5.3",
+      "resolved": "https://registry.npmjs.org/elliptic/-/elliptic-6.5.3.tgz",
+      "integrity": "sha512-IMqzv5wNQf+E6aHeIqATs0tOLeOTwj1QKbRcS3jBbYkl5oLAserA8yJTT7/VyHUYG91PRmPyeQDObKLPpeS4dw==",
       "requires": {
         "bn.js": "^4.4.0",
         "brorand": "^1.0.1",
@@ -3306,6 +3351,14 @@
       "resolved": "https://registry.npmjs.org/functional-red-black-tree/-/functional-red-black-tree-1.0.1.tgz",
       "integrity": "sha1-GwqzvVU7Kg1jmdKcDj6gslIHgyc="
     },
+    "gaze": {
+      "version": "1.1.3",
+      "resolved": "https://registry.npmjs.org/gaze/-/gaze-1.1.3.tgz",
+      "integrity": "sha512-BRdNm8hbWzFzWHERTrejLqwHDfS4GibPoq5wjTPIoJHoBtKGPg3xAFfxmM+9ztbXelxcf2hwQcaz1PtmFeue8g==",
+      "requires": {
+        "globule": "^1.0.0"
+      }
+    },
     "gensync": {
       "version": "1.0.0-beta.1",
       "resolved": "https://registry.npmjs.org/gensync/-/gensync-1.0.0-beta.1.tgz",
@@ -3442,11 +3495,26 @@
         }
       }
     },
+    "globule": {
+      "version": "1.3.2",
+      "resolved": "https://registry.npmjs.org/globule/-/globule-1.3.2.tgz",
+      "integrity": "sha512-7IDTQTIu2xzXkT+6mlluidnWo+BypnbSoEVVQCGfzqnl5Ik8d3e1d4wycb8Rj9tWW+Z39uPWsdlquqiqPCd/pA==",
+      "requires": {
+        "glob": "~7.1.1",
+        "lodash": "~4.17.10",
+        "minimatch": "~3.0.2"
+      }
+    },
     "graceful-fs": {
       "version": "4.2.3",
       "resolved": "https://registry.npmjs.org/graceful-fs/-/graceful-fs-4.2.3.tgz",
       "integrity": "sha512-a30VEBm4PEdx1dRB7MFK7BejejvCvBronbLjht+sHuGYj8PHs7M/5Z+rt5lw551vZ7yfTCj4Vuyy3mSJytDWRQ=="
     },
+    "graceful-readlink": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/graceful-readlink/-/graceful-readlink-1.0.1.tgz",
+      "integrity": "sha1-TK+tdrxi8C+gObL5Tpo906ORpyU="
+    },
     "growl": {
       "version": "1.10.5",
       "resolved": "https://registry.npmjs.org/growl/-/growl-1.10.5.tgz",
@@ -3460,6 +3528,19 @@
       "dev": true,
       "optional": true
     },
+    "handlebars": {
+      "version": "4.7.6",
+      "resolved": "https://registry.npmjs.org/handlebars/-/handlebars-4.7.6.tgz",
+      "integrity": "sha512-1f2BACcBfiwAfStCKZNrUCgqNZkGsAT7UM3kkYtXuLo0KnaVfjKOyf7PRzB6++aK9STyT1Pd2ZCPe3EGOXleXA==",
+      "dev": true,
+      "requires": {
+        "minimist": "^1.2.5",
+        "neo-async": "^2.6.0",
+        "source-map": "^0.6.1",
+        "uglify-js": "^3.1.4",
+        "wordwrap": "^1.0.0"
+      }
+    },
     "har-schema": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/har-schema/-/har-schema-2.0.0.tgz",
@@ -4000,6 +4081,99 @@
       "integrity": "sha1-R+Y/evVa+m+S4VAOaQ64uFKcCZo=",
       "dev": true
     },
+    "istanbul": {
+      "version": "0.4.5",
+      "resolved": "https://registry.npmjs.org/istanbul/-/istanbul-0.4.5.tgz",
+      "integrity": "sha1-ZcfXPUxNqE1POsMQuRj7C4Azczs=",
+      "dev": true,
+      "requires": {
+        "abbrev": "1.0.x",
+        "async": "1.x",
+        "escodegen": "1.8.x",
+        "esprima": "2.7.x",
+        "glob": "^5.0.15",
+        "handlebars": "^4.0.1",
+        "js-yaml": "3.x",
+        "mkdirp": "0.5.x",
+        "nopt": "3.x",
+        "once": "1.x",
+        "resolve": "1.1.x",
+        "supports-color": "^3.1.0",
+        "which": "^1.1.1",
+        "wordwrap": "^1.0.0"
+      },
+      "dependencies": {
+        "escodegen": {
+          "version": "1.8.1",
+          "resolved": "https://registry.npmjs.org/escodegen/-/escodegen-1.8.1.tgz",
+          "integrity": "sha1-WltTr0aTEQvrsIZ6o0MN07cKEBg=",
+          "dev": true,
+          "requires": {
+            "esprima": "^2.7.1",
+            "estraverse": "^1.9.1",
+            "esutils": "^2.0.2",
+            "optionator": "^0.8.1",
+            "source-map": "~0.2.0"
+          }
+        },
+        "esprima": {
+          "version": "2.7.3",
+          "resolved": "https://registry.npmjs.org/esprima/-/esprima-2.7.3.tgz",
+          "integrity": "sha1-luO3DVd59q1JzQMmc9HDEnZ7pYE=",
+          "dev": true
+        },
+        "estraverse": {
+          "version": "1.9.3",
+          "resolved": "https://registry.npmjs.org/estraverse/-/estraverse-1.9.3.tgz",
+          "integrity": "sha1-r2fy3JIlgkFZUJJgkaQAXSnJu0Q=",
+          "dev": true
+        },
+        "glob": {
+          "version": "5.0.15",
+          "resolved": "https://registry.npmjs.org/glob/-/glob-5.0.15.tgz",
+          "integrity": "sha1-G8k2ueAvSmA/zCIuz3Yz0wuLk7E=",
+          "dev": true,
+          "requires": {
+            "inflight": "^1.0.4",
+            "inherits": "2",
+            "minimatch": "2 || 3",
+            "once": "^1.3.0",
+            "path-is-absolute": "^1.0.0"
+          }
+        },
+        "has-flag": {
+          "version": "1.0.0",
+          "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-1.0.0.tgz",
+          "integrity": "sha1-nZ55MWXOAXoA8AQYxD+UKnsdEfo=",
+          "dev": true
+        },
+        "resolve": {
+          "version": "1.1.7",
+          "resolved": "https://registry.npmjs.org/resolve/-/resolve-1.1.7.tgz",
+          "integrity": "sha1-IDEU2CrSxe2ejgQRs5ModeiJ6Xs=",
+          "dev": true
+        },
+        "source-map": {
+          "version": "0.2.0",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.2.0.tgz",
+          "integrity": "sha1-2rc/vPwrqBm03gO9b26qSBZLP50=",
+          "dev": true,
+          "optional": true,
+          "requires": {
+            "amdefine": ">=0.0.4"
+          }
+        },
+        "supports-color": {
+          "version": "3.2.3",
+          "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-3.2.3.tgz",
+          "integrity": "sha1-ZawFBLOVQXHYpklGsq48u4pfVPY=",
+          "dev": true,
+          "requires": {
+            "has-flag": "^1.0.0"
+          }
+        }
+      }
+    },
     "istanbul-lib-coverage": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/istanbul-lib-coverage/-/istanbul-lib-coverage-3.0.0.tgz",
@@ -4768,6 +4942,12 @@
         "invert-kv": "^2.0.0"
       }
     },
+    "lcov-parse": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/lcov-parse/-/lcov-parse-1.0.0.tgz",
+      "integrity": "sha1-6w1GtUER68VhrLTECO+TY73I9+A=",
+      "dev": true
+    },
     "leven": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/leven/-/leven-3.1.0.tgz",
@@ -4847,6 +5027,12 @@
       "integrity": "sha1-7dFMgk4sycHgsKG0K7UhBRakJDg=",
       "dev": true
     },
+    "log-driver": {
+      "version": "1.2.7",
+      "resolved": "https://registry.npmjs.org/log-driver/-/log-driver-1.2.7.tgz",
+      "integrity": "sha512-U7KCmLdqsGHBLeWqYlFA0V0Sl6P08EE1ZrmA9cxjUE0WVqT9qnyVDPz1kzpFEP0jdJuFnasWIfSd7fsaNXkpbg==",
+      "dev": true
+    },
     "log-symbols": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/log-symbols/-/log-symbols-3.0.0.tgz",
@@ -5404,6 +5590,15 @@
         "process-on-spawn": "^1.0.0"
       }
     },
+    "nopt": {
+      "version": "3.0.6",
+      "resolved": "https://registry.npmjs.org/nopt/-/nopt-3.0.6.tgz",
+      "integrity": "sha1-xkZdvwirzU2zWTF/eaxopkayj/k=",
+      "dev": true,
+      "requires": {
+        "abbrev": "1"
+      }
+    },
     "normalize-package-data": {
       "version": "2.5.0",
       "resolved": "https://registry.npmjs.org/normalize-package-data/-/normalize-package-data-2.5.0.tgz",
@@ -7478,6 +7673,13 @@
       "resolved": "https://registry.npmjs.org/typescript/-/typescript-3.8.3.tgz",
       "integrity": "sha512-MYlEfn5VrLNsgudQTVJeNaQFUAI7DkhnOjdpAp4T+ku1TfQClewlbSuTVHiA+8skNBgaf02TL/kLOvig4y3G8w=="
     },
+    "uglify-js": {
+      "version": "3.10.0",
+      "resolved": "https://registry.npmjs.org/uglify-js/-/uglify-js-3.10.0.tgz",
+      "integrity": "sha512-Esj5HG5WAyrLIdYU74Z3JdG2PxdIusvj6IWHMtlyESxc7kcDz7zYlYjpnSokn1UbpV0d/QX9fan7gkCNd/9BQA==",
+      "dev": true,
+      "optional": true
+    },
     "union-value": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/union-value/-/union-value-1.0.1.tgz",
@@ -7683,6 +7885,26 @@
         "makeerror": "1.0.x"
       }
     },
+    "watch-run": {
+      "version": "1.2.5",
+      "resolved": "https://registry.npmjs.org/watch-run/-/watch-run-1.2.5.tgz",
+      "integrity": "sha1-ldNaqn9Zdcj9yP/Tzzv/9YY8oEw=",
+      "requires": {
+        "commander": "~2.9.0",
+        "debug": "~2.6.0",
+        "gaze": "~1.1.2"
+      },
+      "dependencies": {
+        "commander": {
+          "version": "2.9.0",
+          "resolved": "https://registry.npmjs.org/commander/-/commander-2.9.0.tgz",
+          "integrity": "sha1-nJkJQXbhIkDLItbFFGCYQA/g99Q=",
+          "requires": {
+            "graceful-readlink": ">= 1.0.0"
+          }
+        }
+      }
+    },
     "watchpack": {
       "version": "1.6.1",
       "resolved": "https://registry.npmjs.org/watchpack/-/watchpack-1.6.1.tgz",
@@ -8568,6 +8790,12 @@
       "resolved": "https://registry.npmjs.org/word-wrap/-/word-wrap-1.2.3.tgz",
       "integrity": "sha512-Hz/mrNwitNRh/HUAtM/VT/5VH+ygD6DV7mYKZAtHOrbs8U7lvPS6xf7EJKMF0uW1KJCl0H701g3ZGus+muE5vQ=="
     },
+    "wordwrap": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/wordwrap/-/wordwrap-1.0.0.tgz",
+      "integrity": "sha1-J1hIEIkUVqQXHI0CJkQa3pDLyus=",
+      "dev": true
+    },
     "worker-farm": {
       "version": "1.7.0",
       "resolved": "https://registry.npmjs.org/worker-farm/-/worker-farm-1.7.0.tgz",
diff --git a/yarn.lock b/yarn.lock
index fba5965..c061568 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1104,9 +1104,9 @@ bluebird@^3.5.5:
   integrity sha512-XpNj6GDQzdfW+r2Wnn7xiSAd7TM3jzkxGXBGTtWKuSXv1xUV+azxAm8jdWZN06QTQk+2N2XB9jRDkvbmQmcRtg==
 
 bn.js@^4.0.0, bn.js@^4.1.0, bn.js@^4.1.1, bn.js@^4.4.0:
-  version "4.11.8"
-  resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.11.8.tgz#2cde09eb5ee341f484746bb0309b3253b1b1442f"
-  integrity sha512-ItfYfPLkWHUjckQCk8xC+LwxgK8NYcXywGigJgSwOP8Y2iyWT4f2vsZnoOXTTbo+o5yXmIUJ4gn5538SO5S3gA==
+  version "4.11.9"
+  resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.11.9.tgz#26d556829458f9d1e81fc48952493d0ba3507828"
+  integrity sha512-E6QoYqCKZfgatHTdHzs1RRKP7ip4vvm+EyRUeE2RF0NblwVvb0p6jSVeNTOFxPn26QXN2o6SMfNxKp6kU8zQaw==
 
 brace-expansion@^1.1.7:
   version "1.1.11"
@@ -1921,9 +1921,9 @@ ecc-jsbn@~0.1.1:
     safer-buffer "^2.1.0"
 
 elliptic@^6.0.0:
-  version "6.5.2"
-  resolved "https://registry.yarnpkg.com/elliptic/-/elliptic-6.5.2.tgz#05c5678d7173c049d8ca433552224a495d0e3762"
-  integrity sha512-f4x70okzZbIQl/NSRLkI/+tteV/9WqL98zx+SQ69KbXxmVrmjwsNUPn/gYJJ0sHvEak24cZgHIPegRePAtA/xw==
+  version "6.5.3"
+  resolved "https://registry.yarnpkg.com/elliptic/-/elliptic-6.5.3.tgz#cb59eb2efdaf73a0bd78ccd7015a62ad6e0f93d6"
+  integrity sha512-IMqzv5wNQf+E6aHeIqATs0tOLeOTwj1QKbRcS3jBbYkl5oLAserA8yJTT7/VyHUYG91PRmPyeQDObKLPpeS4dw==
   dependencies:
     bn.js "^4.4.0"
     brorand "^1.0.1"