Ruby  2.7.0p0(2019-12-25revision647ee6f091eafcce70ffb75ddf7e121e192ab217)
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. These API takes a C function as a method body
 Exception handlings
 deprecated macro APIs
 CRuby Embedding APIsCRuby interpreter APIs. These are APIs to embed MRI interpreter into your program. These functions are not a part of Ruby extension library API. Extension libraries of Ruby should not depend on these functions
 ruby(1) implementationA part of the implementation of ruby(1) command. Other programs that embed Ruby interpreter do not always need to use these functions
 Core objects and their operations