lgets fileId ?varName?
          Reads the next Tcl list from the file given  by  fileId
          and  discards  the terminating newline character.  This
          command differs from the gets command, in that it reads
          Tcl lists rather than lines.  If the list contains new-
          lines or binary data, then that  newline  or  bytes  of
          zero  will  be  returned as part of the result.  Only a
          newline not quoted as part of the  list  indicates  the
          end of the list.  There is no corresponding command for
          outputting lists, as puts will do this correctly.

          If varName is specified, then the line is placed in the
          variable  by  that name and the return value is a count
          of the number of characters  read  (not  including  the
          newline).   If  the  end  of the file is reached before
          reading any characters then -1 is returned and  varName
          is set to an empty string.  If varName is specified and
          an error occurs,  what  ever  data  was  read  will  be
          returned  in the variable, however the resulting string
          may not be a valid list.

          If varName is not specified then the return value  will
          be  the  line (minus the newline character) or an empty
          string if the end of the file is reached before reading
          any  characters.  An empty string will also be returned
          if a line contains no characters except the newline, so
          eof  may  have to be used to determine what really hap-
          pened.

          The lgets command maybe used to read  and  write  lists
          containing binary data, however translation must be set
          to lf or the data maybe corrupted.

          If lgets is currently supported on non-blocking files.

          This command is provided by Extended Tcl.