crypto-contract-value

The value of an unit of contract diffs in different exchanges, and even in the same exchange it differs in different markets.

For example:

• Each Binance perpetual BTCUSDT contract is valued at 100 USD, and each alt coin contract is valued at 10 USD.
• Each OKEx BTC-USDT-SWAP contract is valued at 0.01 BTC.
• Each OKEx BTC-USD-SWAP contract is valued at 100 USD.
• The contract value of spot markets is always 1.

Given quantity, the number of traded coins/contracts, we can multiply it by contract_value to get the total traded coins/USDs.