I need help with understanding the part of the documentation

Hello fellow rubyists,

Please read the whole post despite the fact it's little long.
I have been reading the pick axe manual and am most inpressed with it.
I fully understand that their are some things that are not explained
till later but I don't think that is what I'm confused on. I have come
to a part in the manual which I don't understand and need some
assistance with the following:

Implementing a SongList Container

Class SongList
  def deleteFirst
    @songs.shift
  end
  def deleteLast
    @songs.pop
  end
end

Deffine =E2=80=9Cdef=E2=80=9D. Is =E2=80=9Cundef=E2=80=9D it's oppisit? i=
.e. it causes an =E2=80=9Cdef=E2=80=9Ded thing
to cease to be =E2=80=9Cdef=E2=80=9Ded?
what does =E2=80=9CdeleteFirst=E2=80=9D and =E2=80=9CdeleteLast=E2=80=9D =
do?
=E2=80=9C@songs=E2=80=9D appears to be an array but what is .shift and .p=
op?

#Here is a more ruby type evaluation of the situation
.pop.is_a?(Popcorn)
  if true add .butter and .salt
end
puts ha ha!

class SongList
  def [](key)
    if key.kind_of?(Integer)
      @songs[key]
    else
      # =E2=80=A6
    end
  end
end

What is =E2=80=9C[]=E2=80=9D for?
Why is the =E2=80=9Cdef=E2=80=9D thing in =E2=80=9C()=E2=80=9D?
What does the line =E2=80=9C      @songs[key]=E2=80=9D have to do with an=
ything?
Why is =E2=80=9Ckey=E2=80=9D in =E2=80=9C[]=E2=80=9D instead of =E2=80=9C=
()=E2=80=9D
Why is =E2=80=9C# ...=E2=80=9D after an =E2=80=9Celse=E2=80=9D statement;=
 in mean =E2=80=9Celse=E2=80=9D must have a
condition to work on right?

Blocks and Iterators


Class SongList
  def [](key)
    if key.kind_of?(Integer)
      return @songs[key]
    else
      for I in [e-mail]
        return @songs[i] if key =3D=3D @songs[i].name
      end
    end
    return nil
  end
end

In the =E2=80=9CI in [e-mail]=E2=80=9D what are the =E2=80=9CI=E2=
=80=9D and =E2=80=9C0=E2=80=9D there for?
There's those =E2=80=9C...=E2=80=9D again what do they do?
Why is their nothing within these "[]" ?

Implementing Iterators


Def fibUpTo(max)
  i1, i2 =3D 1, 1  # parallel assignment
  while i1 <=3D max
    yield i1
    i1, i2 =3D i2, i1+i2
  end
end
fibUpTo(1000) { |f| print f, " " }

what are does =E2=80=9Cyeild=E2=80=9D do? It invoked what part of the cod=
e?
Concerning these characters =E2=80=9C{ |f| print f, " " }=E2=80=9D, why t=
he =E2=80=9C{}=E2=80=9D why are
there =E2=80=9C|=E2=80=9D in the line? What are the =E2=80=9Cf=E2=80=9Ds =
for? What would or could go
in-between the (=E2=80=9C =E2=80=9C)?

class Array
  def find
    for I in 0...size
      value =3D self[i]
      return  value if yield(value)
    end
    return nil
  end
end [1, 3, 5, 7, 9].find {|v| v*v > 30 }

what does the =E2=80=9Cfor I in 0...size=E2=80=9D statement do exactly? Y=
ou have =E2=80=9Cfor=E2=80=9D
which I understand, but then you have an =E2=80=9CI=E2=80=9D which is not=
 an object or
an integer or a string or a float. Then an =E2=80=9Cin=E2=80=9D which doe=
s what?
Followed by a =E2=80=9C0=E2=80=9D then =E2=80=9C...=E2=80=9D then =E2=80=9C=
size=E2=80=9D and by then I'm totally
confused.

I like Ruby and I'm willing to read all the documentation that you
create but it will not help me if I don't get it.

1: help me to understand the documentation listed above.

-- =

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