How to use the qtconsole.qt.QtGui.QTextCursor function in qtconsole

elif key == QtCore.Qt.Key_Greater:
                self._control.moveCursor(QtGui.QTextCursor.End)
                intercepted = True

            elif key == QtCore.Qt.Key_Less:
                self._control.setTextCursor(self._get_prompt_cursor())
                intercepted = True

        #------ No modifiers ---------------------------------------------------

        else:
            if shift_down:
                anchormode = QtGui.QTextCursor.KeepAnchor
            else:
                anchormode = QtGui.QTextCursor.MoveAnchor

            if key == QtCore.Qt.Key_Escape:
                self._keyboard_quit()
                intercepted = True

            elif key == QtCore.Qt.Key_Up:
                if self._reading or not self._up_pressed(shift_down):
                    intercepted = True
                else:
                    prompt_line = self._get_prompt_cursor().blockNumber()
                    intercepted = cursor.blockNumber() <= prompt_line

            elif key == QtCore.Qt.Key_Down:
                if self._reading or not self._down_pressed(shift_down):
                    intercepted = True
                else:

def _current_text_cursor(self):
        """ Returns a cursor with text between the start position and the
            current position selected.
        """
        cursor = self._text_edit.textCursor()
        if cursor.position() >= self._start_position:
            cursor.setPosition(self._start_position,
                               QtGui.QTextCursor.KeepAnchor)
        return cursor

def _auto_call_tip(self):
        """Trigger call tip automatically on open parenthesis
        
        Call tips can be requested explcitly with `_call_tip`.
        """
        cursor = self._get_cursor()
        cursor.movePosition(QtGui.QTextCursor.Left)
        if cursor.document().characterAt(cursor.position()) == '(':
            # trigger auto call tip on open paren
            self._call_tip()

def _selection_for_character(self, position):
        """ Convenience method for selecting a character.
        """
        selection = QtGui.QTextEdit.ExtraSelection()
        cursor = self._text_edit.textCursor()
        cursor.setPosition(position)
        cursor.movePosition(QtGui.QTextCursor.NextCharacter,
                            QtGui.QTextCursor.KeepAnchor)
        selection.cursor = cursor
        selection.format = self.format
        return selection

def _clear_temporary_buffer(self):
        """ Clears the "temporary text" buffer, i.e. all the text following
            the prompt region.
        """
        # Select and remove all text below the input buffer.
        cursor = self._get_prompt_cursor()
        prompt = self._continuation_prompt.lstrip()
        if(self._temp_buffer_filled):
            self._temp_buffer_filled = False
            while cursor.movePosition(QtGui.QTextCursor.NextBlock):
                temp_cursor = QtGui.QTextCursor(cursor)
                temp_cursor.select(QtGui.QTextCursor.BlockUnderCursor)
                text = temp_cursor.selection().toPlainText().lstrip()
                if not text.startswith(prompt):
                    break
        else:
            # We've reached the end of the input buffer and no text follows.
            return
        cursor.movePosition(QtGui.QTextCursor.Left) # Grab the newline.
        cursor.movePosition(QtGui.QTextCursor.End,
                            QtGui.QTextCursor.KeepAnchor)
        cursor.removeSelectedText()

        # After doing this, we have no choice but to clear the undo/redo
        # history. Otherwise, the text is not "temporary" at all, because it
        # can be recalled with undo/redo. Unfortunately, Qt does not expose
        # fine-grained control to the undo/redo system.
        if self._control.isUndoRedoEnabled():

if self._history_index == len(self._history) or \
                not (self._history_prefix == '' and at_eol) or \
                not (self._get_edited_history(self._history_index)[:pos] == input_buffer[:pos]):
                self._history_prefix = input_buffer[:pos]

            # Perform the search.
            self.history_previous(self._history_prefix,
                                    as_prefix=not shift_modifier)

            # Go to the first line of the prompt for seemless history scrolling.
            # Emulate readline: keep the cursor position fixed for a prefix
            # search.
            cursor = self._get_prompt_cursor()
            if self._history_prefix:
                cursor.movePosition(QtGui.QTextCursor.Right,
                                    n=len(self._history_prefix))
            else:
                cursor.movePosition(QtGui.QTextCursor.EndOfBlock)
            self._set_cursor(cursor)

            return False

        return True

def _get_block_plain_text(self, block):
        """ Given a QTextBlock, return its unformatted text.
        """
        cursor = QtGui.QTextCursor(block)
        cursor.movePosition(QtGui.QTextCursor.StartOfBlock)
        cursor.movePosition(QtGui.QTextCursor.EndOfBlock,
                            QtGui.QTextCursor.KeepAnchor)
        return cursor.selection().toPlainText()

intercepted = True

            elif key == QtCore.Qt.Key_O:
                if self._page_control and self._page_control.isVisible():
                    self._page_control.setFocus()
                intercepted = True

            elif key == QtCore.Qt.Key_U:
                if self._in_buffer(position):
                    cursor.clearSelection()
                    start_line = cursor.blockNumber()
                    if start_line == self._get_prompt_cursor().blockNumber():
                        offset = len(self._prompt)
                    else:
                        offset = len(self._continuation_prompt)
                    cursor.movePosition(QtGui.QTextCursor.StartOfBlock,
                                        QtGui.QTextCursor.KeepAnchor)
                    cursor.movePosition(QtGui.QTextCursor.Right,
                                        QtGui.QTextCursor.KeepAnchor, offset)
                    self._kill_ring.kill_cursor(cursor)
                    self._set_cursor(cursor)
                intercepted = True

            elif key == QtCore.Qt.Key_Y:
                self._keep_cursor_in_buffer()
                self._kill_ring.yank()
                intercepted = True

            elif key in (QtCore.Qt.Key_Backspace, QtCore.Qt.Key_Delete):
                if key == QtCore.Qt.Key_Backspace:
                    cursor = self._get_word_start_cursor(position)
                else: # key == QtCore.Qt.Key_Delete

# Regular backwards deletion
                else:
                    anchor = cursor.anchor()
                    if anchor == position:
                        intercepted = not self._in_buffer(position - 1)
                    else:
                        intercepted = not self._in_buffer(min(anchor, position))

            elif key == QtCore.Qt.Key_Delete:

                # Line deletion (remove continuation prompt)
                if not self._reading and self._in_buffer(position) and \
                        cursor.atBlockEnd() and not cursor.hasSelection():
                    cursor.movePosition(QtGui.QTextCursor.NextBlock,
                                        QtGui.QTextCursor.KeepAnchor)
                    cursor.movePosition(QtGui.QTextCursor.Right,
                                        QtGui.QTextCursor.KeepAnchor,
                                        len(self._continuation_prompt))
                    cursor.removeSelectedText()
                    intercepted = True

                # Regular forwards deletion:
                else:
                    anchor = cursor.anchor()
                    intercepted = (not self._in_buffer(anchor) or
                                   not self._in_buffer(position))

        # Don't move the cursor if Control/Cmd is pressed to allow copy-paste
        # using the keyboard in any part of the buffer. Also, permit scrolling
        # with Page Up/Down keys. Finally, if we're executing, don't move the
        # cursor (if even this made sense, we can't guarantee that the prompt
        # position is still valid due to text truncation).

def show_items(self, cursor, items, prefix_length=0):
        """ Shows the completion widget with 'items' at the position specified
            by 'cursor'.
        """
        if not items :
            return
        # Move cursor to start of the prefix to replace it
        # when a item is selected
        cursor.movePosition(QtGui.QTextCursor.Left, n=prefix_length)
        self._start_position = cursor.position()
        self._consecutive_tab = 1
        # Calculate the number of characters available.
        width = self._text_edit.document().textWidth()
        char_width = QtGui.QFontMetrics(self._console_widget.font).width(' ')
        displaywidth = int(max(10, (width / char_width) - 1))
        items_m, ci = text.compute_item_matrix(items, empty=' ',
                                               displaywidth=displaywidth)
        self._sliding_interval = SlidingInterval(len(items_m)-1)

        self._items = items_m
        self._size = (ci['rows_numbers'], ci['columns_numbers'])
        self._old_cursor = cursor
        self._index = (0, 0)
        sjoin = lambda x : [ y.ljust(w, ' ') for y, w in zip(x, ci['columns_width'])]
        self._justified_items = list(map(sjoin, items_m))