'returns the expected position of a cell in pixels from the top-left
of the sheet. For example, A1 anchor should be (0,0).
:rtype: tuple(int, int)'

@property
def anchor(self):

    left_columns = (column_index_from_string(self.column) - 1)
    column_dimensions = self.parent.column_dimensions
    left_anchor = 0
    default_width = points_to_pixels(DEFAULT_COLUMN_WIDTH)
    for col_idx in range(left_columns):
        letter = get_column_letter((col_idx + 1))
        if (letter in column_dimensions):
            cdw = (column_dimensions.get(letter).width or default_width)
            if (cdw > 0):
                left_anchor += points_to_pixels(cdw)
                continue
        left_anchor += default_width
    row_dimensions = self.parent.row_dimensions
    top_anchor = 0
    top_rows = (self.row - 1)
    default_height = points_to_pixels(DEFAULT_ROW_HEIGHT)
    for row_idx in range(1, (top_rows + 1)):
        if (row_idx in row_dimensions):
            rdh = (row_dimensions[row_idx].height or default_height)
            if (rdh > 0):
                top_anchor += points_to_pixels(rdh)
                continue
        top_anchor += default_height
    return (left_anchor, top_anchor)
