I'd rather pay with with utility isEvenCoins, rather than with USD.<p>Also, our entire stack is GraphQL-based, so we must have a GraphQL API according to this schema:<p><pre><code> schema {
query: Query
mutation: Mutation
subscription: Subscription
}
type Query {
balance: Int!
isEven(input: isEvenInput!): isEvenPayload!
}
type Mutation {
depositCoins(amount: Int!): DepositPayload!
withdrawCoins(amount: Int!): WithdrawPayload!
}
type Subscription {
coinsDeposited: Int!
coinsWithdrawn: Int!
coinsSpent: Int!
}
input isEvenInput {
number: Int!
gas: Int!
}
type isEvenPayload {
result: bool
balanceLeft: Int!
isError: bool!
errMsg: String
}
type DepositPayload {
newBalance: Int!
isError: bool!
errMsg: String
}
type WithdrawPayload {
newBalance: Int!
isError: bool!
errMsg: String
}</code></pre>