+bitcoin = { version = "0.29.0", default-features = false, features = ["secp-recovery"] }
+
+hashbrown = { version = "0.8", optional = true }
+hex = { version = "0.4", optional = true }
+regex = { version = "1.5.6", optional = true }
+backtrace = { version = "0.3", optional = true }