feat(PocomathInstance): Add use(deps, imp) function for defining signatures

src/bigint/add.mjs

@@ -1,5 +1,6 @@
+import {use} from '../core/PocomathInstance.mjs'
 export {Types} from './Types/bigint.mjs'
 
 export const add = {
-   '...bigint': [[], addends => addends.reduce((x,y) => x+y, 0n)],
+   '...bigint': use([], addends => addends.reduce((x,y) => x+y, 0n))
 }

src/bigint/negate.mjs

@@ -1,3 +1,4 @@
+import {use} from '../core/PocomathInstance.mjs'
 export {Types} from './Types/bigint.mjs'
 
-export const negate = {bigint: [[], b => -b ]}
+export const negate = {bigint: use([], b => -b)}

src/core/PocomathInstance.mjs

@@ -1,6 +1,10 @@
 /* Core of pocomath: create an instance */
 import typed from 'typed-function'
 
+export function use(dependencies, implementation) {
+   return [dependencies, implementation]
+}
+
 export default class PocomathInstance {
    /* Disallowed names for ops; beware, this is slightly non-DRY
     * in that if a new top-level PocomathInstance method is added, its name