MLLP.TCPContract.connect

You're seeing just the callback connect, go back to MLLP.TCPContract module for more information.
Link to this callback

connect( address, port, options, timeout )

Specs

connect(
  address :: :inet.socket_address() | :inet.hostname(),
  port :: :inet.port_number(),
  options :: [:gen_tcp.connect_option()],
  timeout :: timeout()
) :: {:ok, :gen_tcp.socket()} | {:error, any()}