Explain any four functions of the Matplotlib library.

The Matplotlib library provides various functions to create and customise plots. Four important functions are explained below:

1. plot(): This function is used to plot data on a graph. It is used to draw line plots by specifying values for the x-axis and y-axis.

2. xlabel(): This function is used to assign a label to the x-axis of the graph.

3. ylabel(): This function is used to assign a label to the y-axis of the graph.

4. title(): This function is used to assign a title to the graph, which describes what the graph represents.