Modules with selected groups of units

The si module includes all of the base and derived SI units. The constants module contains all constants (physical quantities which are not units). These modules contain all of the constants and units with the indicated dimension:

These modules require that the SI units are defined in the selected INI files. BIPM.ini contains those definitions, and it is loaded by default.

Each module can only be reloaded once.[1]



This is typical in Python. From imp.reload():

“In many cases, however, extension modules are not designed to be initialized more than once, and may fail in arbitrary ways when reloaded.”