anchor.diff:  %%            User     = string()
   %%            Password = string()
   %%            Database = string()
  -%%            LogFun   = undefined | function() of arity 3
  +%%            LogFun   = undefined | mysql_log_fun()
   %%
   %%            Pid    = pid()
   %%            Reason = string()
  
positive.code: %%            User     = string()
  %%            Password = string()
  %%            Database = string()
  %%            LogFun   = undefined | function() of arity 3
  %%            Parent   = pid() of process starting this mysql_conn
  %%
  %% @doc     Connect to a MySQL server, log in and chooses a database.
  
negative.code: %%            RecvPid  = pid() "mysql_recv process"
  %%            User     = string()
  %%            Password = string()
  %%            LogFun   = undefined | mysql_log_fun()
  %%
  %%            Reason = string()
  %%
  