pub unsafe extern "C" fn secp256k1_schnorrsig_sign(
cx: *const Context,
sig: *mut u8,
msg32: *const u8,
keypair: *const KeyPair,
noncefp: Option<unsafe extern "C" fn(*mut u8, *const u8, *const u8, *const u8, *const u8, *mut c_void) -> i32>,
noncedata: *const c_void
) -> i32