/// Returns a validated block header of the source's best chain tip.
///
/// Upon success, the returned header can be used to initialize [`SpvClient`]. Useful during a fresh
/// start when there are no chain listeners to sync yet.
///
/// [`SpvClient`]: crate::SpvClient
/// Returns a validated block header of the source's best chain tip.
///
/// Upon success, the returned header can be used to initialize [`SpvClient`]. Useful during a fresh
/// start when there are no chain listeners to sync yet.
///
/// [`SpvClient`]: crate::SpvClient