Function get_num_tx 

pub fn get_num_tx(db: &BlockchainDatabase, tx_ro: &Snapshot) -> DbResult<u64>

How many [Transaction]s are there?

This returns the amount of transactions currently stored.

For example:

• 0 transactions exist => returns 0
• 1 transactions exist => returns 1
• 5 transactions exist => returns 5
• etc