define, operate and manipulate physical quantities - Python 3.x

 Pint is Python module/package to define, operate and manipulate physical
 quantities: the product of a numerical value and a unit of measurement. It
 allows arithmetic operations between them and conversions from and to
 different units.
 .
 It is distributed with a comprehensive list of physical units, prefixes and
 constants. Due to its modular design, you can extend (or even rewrite!) the
 complete list without changing the source code.
 .
 This package contains the Python 3.x module.