ReferredArea class

Represents a referred area by the formula.

The ReferredArea type exposes the following members:

Property	Description
is_external_link	Indicates whether this is an external link.
external_file_name	Get the external file name if this is an external reference.
sheet_name	Indicates which sheet this reference is in.
sheet_names	Names of all the worksheets this instance references to.
is_entire_row	Indicates whether this area contains all columns(entire row).
is_entire_column	Indicates whether this area contains all rows(entire column).
is_area	Indicates whether this is an area.
end_column	The end column of the area.
start_column	The start column of the area.
end_row	The end row of the area.
start_row	The start row of the area.

Method	Description
`get_values(self)`	Gets cell values in this area.
`get_values(self, calculate_formulas)`	Gets cell values in this area.
`get_value(self, row_offset, col_offset)`	Gets cell value with given offset from the top-left of this area.
`get_value(self, row_offset, col_offset, calculate_formulas)`	Gets cell value with given offset from the top-left of this area.