class Encoding: An \Encoding instance represents a character encoding usable in Ruby. It is defined as a constant under the \Encoding namespace.| docs.ruby-lang.org
class ArgumentError: Raised when the arguments are wrong and there isn't a more specific Exception class. passing the wrong number of arguments [1, 2, 3].| docs.ruby-lang.org
class Integer: An \Integer object represents an integer value. literals.| docs.ruby-lang.org
class String: A +String+ object has an arbitrary sequence of bytes, typically representing text or binary data. new or as literals.| docs.ruby-lang.org
class Regexp: en. wikipedia.| docs.ruby-lang.org