nested definitions in ruby?

gistfile1.txt

def hoge
  p def fuga
   p "called fuga"
  end
  fuga
end

hoge
fuga

# => nil
# => "called fuga"
# => "called fuga"

def hoge
p def fuga
p "called fuga in hoge"
end
fuga
end

def foo
p def fuga
p "called fuga in foo"
end
end

hoge
foo
fuga
hoge
fuga

=> nil

=> "called fuga in hoge"

=> nil

=> "called fuga in foo"

=> nil

=> "called fuga in hoge"

=> "called fuga in hoge"

$ ruby --dump=insns fuga.rb
== disasm: RubyVM::InstructionSequence:main@fuga.rb=================
0000 trace 1 ( 3)
0002 putspecialobject 1
0004 putspecialobject 2
0006 putobject :hoge
0008 putiseq hoge
0010 send :"core#define_method", 3, nil, 0, ic:0
0016 pop
0017 trace 1 ( 10)
0019 putspecialobject 1
0021 putspecialobject 2
0023 putobject :foo
0025 putiseq foo
0027 send :"core#define_method", 3, nil, 0, ic:1
0033 pop
0034 trace 1 ( 16)
0036 putself
0037 send :hoge, 0, nil, 24, ic:2
0043 pop
0044 trace 1 ( 17)
0046 putself
0047 send :foo, 0, nil, 24, ic:3
0053 pop
0054 trace 1 ( 18)
0056 putself
0057 send :fuga, 0, nil, 24, ic:4
0063 pop
0064 trace 1 ( 19)
0066 putself
0067 send :hoge, 0, nil, 24, ic:5
0073 pop
0074 trace 1 ( 20)
0076 putself
0077 send :fuga, 0, nil, 24, ic:6
0083 leave
== disasm: RubyVM::InstructionSequence:hoge@fuga.rb===================
0000 trace 8 ( 3)
0002 trace 1 ( 6)
0004 putself
0005 putspecialobject 1 ( 4)
0007 putspecialobject 2
0009 putobject :fuga
0011 putiseq fuga
0013 send :"core#define_method", 3, nil, 0, ic:0
0019 send :p, 1, nil, 8, ic:1 ( 6)
0025 pop
0026 trace 1 ( 7)
0028 putself
0029 send :fuga, 0, nil, 24, ic:2
0035 trace 16 ( 8)
0037 leave ( 7)
== disasm: RubyVM::InstructionSequence:fuga@fuga.rb===================
0000 trace 8 ( 4)
0002 trace 1 ( 5)
0004 putself
0005 putstring "called fuga in hoge"
0007 send :p, 1, nil, 8, ic:0
0013 trace 16 ( 6)
0015 leave
== disasm: RubyVM::InstructionSequence:foo@fuga.rb====================
0000 trace 8 ( 10)
0002 trace 1 ( 13)
0004 putself
0005 putspecialobject 1 ( 11)
0007 putspecialobject 2
0009 putobject :fuga
0011 putiseq fuga
0013 send :"core#define_method", 3, nil, 0, ic:0
0019 send :p, 1, nil, 8, ic:1 ( 13)
0025 trace 16 ( 14)
0027 leave ( 11)
== disasm: RubyVM::InstructionSequence:fuga@fuga.rb===================
0000 trace 8 ( 11)
0002 trace 1 ( 12)
0004 putself
0005 putstring "called fuga in foo"
0007 send :p, 1, nil, 8, ic:0
0013 trace 16 ( 13)
0015 leave ( 12)