madgraph.core.base_objects: Definitions of all basic objects used in the core code: particle,
interaction, model, leg, vertex, process, ...
madgraph.core.color_algebra: Classes and methods required for all calculations related to SU(N)
color algebra.
madgraph.core.color_amp: Classes, methods and functions required to write QCD color
information for a diagram and build a color basis, and to square a
QCD color string for squared diagrams and interference terms.