module Kernel
module Psych
module Psych::Handlers
module Psych::JSON
module Psych::JSON::RubyEvents
module Psych::JSON::YAMLEvents
module Psych::Nodes
module Psych::Streaming
module Psych::Streaming::ClassMethods
module Psych::Visitors
class Object
class Psych::AliasesNotEnabled
class Psych::AnchorNotDefined
class Psych::BadAlias
class Psych::ClassLoader
class Psych::ClassLoader::Restricted
class Psych::Coder
class Psych::Config
class Psych::DisallowedClass
class Psych::Exception
class Psych::Handler
class Psych::Handler::DumperOptions
class Psych::Handlers::DocumentStream
class Psych::Handlers::Recorder
class Psych::JSON::Stream
class Psych::JSON::Stream::Emitter
class Psych::JSON::TreeBuilder
class Psych::Nodes::Alias
class Psych::Nodes::Document
class Psych::Nodes::Mapping
class Psych::Nodes::Node
class Psych::Nodes::Scalar
class Psych::Nodes::Sequence
class Psych::Nodes::Stream
class Psych::Omap
class Psych::Parser
class Psych::Parser::Mark
class Psych::ScalarScanner
class Psych::Set
class Psych::Stream
class Psych::Stream::Emitter
class Psych::SyntaxError
class Psych::TreeBuilder
class Psych::Visitors::DepthFirst
class Psych::Visitors::Emitter
class Psych::Visitors::JSONTree
class Psych::Visitors::NoAliasRuby
class Psych::Visitors::RestrictedYAMLTree
class Psych::Visitors::ToRuby
class Psych::Visitors::Visitor
class Psych::Visitors::YAMLTree
class Psych::Visitors::YAMLTree::Registrar
psych
5.1.1.1
# merge_key
def merge_key hash, key, val end