Provides a Graph class for creating graphs from .csv data files.
A graph of data from a CSV file.
Add date labels to the graph.
Generate the graph.
Try to guess the date format used in the current .csv file, by reading from the first row of the date_column column.
Save the graph to filename. The format is determined by the extension of filename; if it’s not png, svg, or pdf, then a ValueError is raised.
Display the graph in a GUI window.