Add market buy option

index.js

@@ -6,6 +6,11 @@ const getEnv = (...vars) => vars.map(name => {
   assert(value, `Provide the ${name} environment variable.`)
   return value
 })
+const getEnvOpt = (varname, defaultValue, allowedValues) => {
+  const value = process.env[varname] || defaultValue
+  if (allowedValues) assert(allowedValues.includes(value), `The ${varname} environment variable must be one of ${allowedValues.map(v => `"${v}"`).join(", ")}.`)
+  return value
+}
 const command = process.argv[2].replace('--cmd=', '')
 const validate = process.argv.includes('--validate') || process.env['KRAKEN_DRY_RUN_PLACE_NO_ORDER']
 
@@ -15,7 +20,7 @@ const validate = process.argv.includes('--validate') || process.env['KRAKEN_DRY_
     const kraken = new Kraken(apiKey, secret)
 
     const cmd = require(`./commands/${command}`)
-    await cmd(kraken, validate, getEnv)
+    await cmd(kraken, validate, { getEnv, getEnvOpt })
 
     if (validate) console.log('\n🚨  THIS WAS JUST A VALIDATION RUN!')
   } catch (err) {