 
   @doc """
   Returns the pid or port identifier with the registered name.
-  Returns nil if the name is not registered.
+  Returns `nil` if the name is not registered.
 
   See http://www.erlang.org/doc/man/erlang.html#whereis-1 for more info.
   """


  @doc """
  Sets the group leader of `pid` to `leader`. Typically, this is used when a processes
  started from a certain shell should have another group leader than `:init`.
  """
  @spec group_leader(pid, leader :: pid) :: true
  def group_leader(pid, leader) do

  end

  @doc """
  Returns information about the process identified by `pid`
  or `nil` if the process is not alive.

  See http://www.erlang.org/doc/man/erlang.html#process_info-2 for more info.
  """
