Function bip54_deployment_mainnet 

pub fn bip54_deployment_mainnet() -> Bip9Deployment

Returns the BIP54 deployment for mainnet when using version-bits activation.

Uses bit 15 and no time bounds so that once 95% of blocks in a 2016-block period signal the bit, BIP54 is considered active. If the network assigns a different bit or timeline, pass a custom Bip9Deployment to activation_height_from_headers instead.