Ruby  2.7.2p137(2020-10-01revision5445e0435260b449decf2ac16f9d09bae3cafe72)
Modules
Here is a list of all modules:
[detail level 123]
 Classes and their hierarchy.
 Defining methodsThere are some APIs to define a method from C
 Exception handlings
 deprecated macro APIs
 CRuby Embedding APIsCRuby interpreter APIs
 ruby(1) implementationA part of the implementation of ruby(1) command
 Core objects and their operations