TLS1_CK_ECDHE_ECDSA_CHACHA20_POLY1305

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
extern (C) nothrow @nogc
enum TLS1_CK_ECDHE_ECDSA_CHACHA20_POLY1305 = 0x0300CCA9;

Meta