
  -spec erlang:dist_ctrl_get_data(DHandle) -> {Size, Data} | Data | none
                                     when
                                         Size :: non_neg_integer(),
                                         DHandle :: dist_handle(),
                                         Data :: iovec().

Since:
  OTP 21.0

  Get distribution channel data from the local node that is to be
  passed to the remote node. The distribution channel is identified
  by DHandle. If no data is available, the atom none is
  returned. One can request to be informed by a message when more
  data is available by calling 
  erlang:dist_ctrl_get_data_notification(DHandle).

  The returned value when there are data available depends on the
  value of the get_size option configured on the distribution
  channel identified by DHandle. For more information see the
  documentation of the get_size option for the 
  erlang:dist_ctrl_set_opt/3 function.

  Note:
    Only the process registered as distribution controller for the
    distribution channel identified by DHandle is allowed to
    call this function.

  This function is used when implementing an alternative
  distribution carrier using processes as distribution controllers. 
  DHandle is retrieved via the callback f_handshake_complete.
  More information can be found in the documentation of ERTS User's
  Guide ➜ How to implement an Alternative Carrier for the Erlang
  Distribution ➜ Distribution Module.
