TM1637 is a chip for driving 7-segment displays. There are several modules using this chip to form a 4 digit numerical display module (sometimes called "Digital Tube"). These modules are available, for example, from DX and SeeedStudio.
Note: the TM1637 has also keyboard input capability, which is not implemented in this library.
The display module has 4 pins:
TM1637Display object is created, the clock and data pin numbers are passed as arguments and get bound.