feat(gcd,lcm): Allow arbitrarily many arguments

And add an 'associate' predicate for two complex numbers to check the results

src/generic/arithmetic.mjs

@@ -3,6 +3,7 @@ import {reducingOperation} from './reducingOperation.mjs'
 export * from './Types/generic.mjs'
 
 export const add = reducingOperation
+export const gcd = reducingOperation
 export {lcm} from './lcm.mjs'
 export {mean} from './mean.mjs'
 export {mod} from './mod.mjs'

src/generic/lcm.mjs

@@ -1,3 +1,5 @@
+import {reducingOperation} from './reducingOperation.mjs'
+
 export const lcm = {
    'T,T': ({
       'multiply(T,T)': multT,
@@ -5,3 +7,4 @@ export const lcm = {
       'gcd(T,T)': gcdT
    }) => (a,b) => multT(quotT(a, gcdT(a,b)), b)
 }
+Object.assign(lcm, reducingOperation)