====== function: changeTempo ======

===== Description =====

This function is a method of the MusicalEnvironment class. It is called with a floating point number specifying a tempo beats per minute. After calling this method, the tempo immediately increases or decreases to the specified BPM.

===== Syntax =====

===== Parameters =====

a floating point number specifying a tempo in beats per minute

===== Return Value =====

===== Example =====